diff --git a/CHANGELOG.md b/CHANGELOG.md
index f19d999..3fdd6cd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -562,10 +562,6 @@
   * Renamed `E`, `LN10`, `LN`, `LOG2E`, `LOG10E`, `PI`, `SQRT1_2` and `SQRT2`
     to `e`, `ln10`, `ln`, `log2e`, `log10e`, `pi`, `sqrt1_2` and `sqrt2`.
 
-* `dart.mirrors`
-  * Added `IsolateMirror.loadUri`, which allows dynamically loading additional
-    code.
-
 <!--
 Still need entries for all changes to dart:svg since 1.x
 -->
diff --git a/runtime/bin/loader.cc b/runtime/bin/loader.cc
index ba0dc63..64b76f5 100644
--- a/runtime/bin/loader.cc
+++ b/runtime/bin/loader.cc
@@ -7,7 +7,6 @@
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 #include "bin/dfe.h"
-#include "bin/error_exit.h"
 #include "bin/extensions.h"
 #include "bin/file.h"
 #include "bin/gzip.h"
@@ -661,6 +660,7 @@
   if (Dart_IsError(result)) {
     return result;
   }
+  Dart_Isolate current = Dart_CurrentIsolate();
   if (tag == Dart_kKernelTag) {
     uint8_t* kernel_buffer = NULL;
     intptr_t kernel_buffer_size = 0;
@@ -687,6 +687,7 @@
 
     return Extensions::LoadExtension("/", absolute_path, library);
   }
+  ASSERT(Dart_IsKernelIsolate(current) || !dfe.UseDartFrontend());
   if (tag != Dart_kScriptTag) {
     // Special case for handling dart: imports and parts.
     // Grab the library's url.
@@ -764,25 +765,9 @@
   if (DartUtils::IsDartExtensionSchemeURL(url_string)) {
     loader->SendImportExtensionRequest(url, Dart_LibraryUrl(library));
   } else {
-    if (dfe.CanUseDartFrontend() && dfe.UseDartFrontend()) {
-      ASSERT(tag == Dart_kImportTag);
-      char* error = NULL;
-      int exit_code = 0;
-      uint8_t* kernel_buffer = NULL;
-      intptr_t kernel_buffer_size = -1;
-      dfe.CompileAndReadScript(url_string, &kernel_buffer, &kernel_buffer_size,
-                               &error, &exit_code, true /* strong */, NULL);
-      if (exit_code == 0) {
-        return Dart_LoadLibraryFromKernel(kernel_buffer, kernel_buffer_size);
-      } else if (exit_code == kCompilationErrorExitCode) {
-        Dart_Handle result = Dart_NewCompilationError(error);
-        free(error);
-        return result;
-      } else {
-        Dart_Handle result = Dart_NewApiError(error);
-        free(error);
-        return result;
-      }
+    if (dfe.CanUseDartFrontend() && dfe.UseDartFrontend() &&
+        !Dart_IsKernelIsolate(current)) {
+      FATAL("Loader should not be called to compile scripts to kernel.");
     } else {
       loader->SendRequest(
           tag, url,
diff --git a/runtime/include/dart_api.h b/runtime/include/dart_api.h
index c52f569..e287914 100644
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -351,7 +351,6 @@
  * \param error the error message.
  */
 DART_EXPORT Dart_Handle Dart_NewApiError(const char* error);
-DART_EXPORT Dart_Handle Dart_NewCompilationError(const char* error);
 
 /**
  * Produces a new unhandled exception error handle.
diff --git a/runtime/lib/mirrors.cc b/runtime/lib/mirrors.cc
index 47307c3..3524eef 100644
--- a/runtime/lib/mirrors.cc
+++ b/runtime/lib/mirrors.cc
@@ -9,7 +9,6 @@
 #include "vm/class_finalizer.h"
 #include "vm/compiler/frontend/kernel_to_il.h"
 #include "vm/compiler/jit/compiler.h"
-#include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
 #include "vm/flags.h"
@@ -759,95 +758,6 @@
   return CreateIsolateMirror();
 }
 
-static void ThrowLanguageError(const char* message) {
-  const Error& error =
-      Error::Handle(LanguageError::New(String::Handle(String::New(message))));
-  Exceptions::PropagateError(error);
-}
-
-DEFINE_NATIVE_ENTRY(IsolateMirror_loadUri, 1) {
-  GET_NON_NULL_NATIVE_ARGUMENT(String, uri, arguments->NativeArgAt(0));
-
-  Dart_LibraryTagHandler handler = isolate->library_tag_handler();
-  if (handler == NULL) {
-    ThrowLanguageError("no library handler registered");
-  }
-
-  // Canonicalize library URI.
-  String& canonical_uri = String::Handle(zone);
-  if (uri.StartsWith(Symbols::DartScheme())) {
-    canonical_uri = uri.raw();
-  } else {
-    isolate->BlockClassFinalization();
-    Object& result = Object::Handle(zone);
-    {
-      TransitionVMToNative transition(thread);
-      Api::Scope api_scope(thread);
-      Dart_Handle retval = handler(
-          Dart_kCanonicalizeUrl,
-          Api::NewHandle(thread, isolate->object_store()->root_library()),
-          Api::NewHandle(thread, uri.raw()));
-      result = Api::UnwrapHandle(retval);
-    }
-    isolate->UnblockClassFinalization();
-    if (result.IsError()) {
-      if (result.IsLanguageError()) {
-        Exceptions::ThrowCompileTimeError(LanguageError::Cast(result));
-      }
-      Exceptions::PropagateError(Error::Cast(result));
-    } else if (!result.IsString()) {
-      ThrowLanguageError("library handler failed URI canonicalization");
-    }
-
-    canonical_uri ^= result.raw();
-  }
-
-  // Create a new library if it does not exist yet.
-  Library& library =
-      Library::Handle(zone, Library::LookupLibrary(thread, canonical_uri));
-  if (library.IsNull()) {
-    library = Library::New(canonical_uri);
-    library.Register(thread);
-  }
-
-  // Ensure loading started.
-  if (library.LoadNotStarted()) {
-    library.SetLoadRequested();
-
-    isolate->BlockClassFinalization();
-    Object& result = Object::Handle(zone);
-    {
-      TransitionVMToNative transition(thread);
-      Api::Scope api_scope(thread);
-      Dart_Handle retval = handler(
-          Dart_kImportTag,
-          Api::NewHandle(thread, isolate->object_store()->root_library()),
-          Api::NewHandle(thread, canonical_uri.raw()));
-      result = Api::UnwrapHandle(retval);
-    }
-    isolate->UnblockClassFinalization();
-    if (result.IsError()) {
-      if (result.IsLanguageError()) {
-        Exceptions::ThrowCompileTimeError(LanguageError::Cast(result));
-      }
-      Exceptions::PropagateError(Error::Cast(result));
-    }
-  }
-
-  if (!library.Loaded()) {
-    // This code assumes a synchronous tag handler (which dart::bin and tonic
-    // provide). Strictly though we should complete a future in response to
-    // Dart_FinalizeLoading.
-    UNIMPLEMENTED();
-  }
-
-  if (!ClassFinalizer::ProcessPendingClasses()) {
-    Exceptions::PropagateError(Error::Handle(thread->sticky_error()));
-  }
-
-  return CreateLibraryMirror(thread, library);
-}
-
 DEFINE_NATIVE_ENTRY(Mirrors_makeLocalClassMirror, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(AbstractType, type, arguments->NativeArgAt(0));
   PROPAGATE_IF_MALFORMED(type);
diff --git a/runtime/lib/mirrors_impl.dart b/runtime/lib/mirrors_impl.dart
index 6d83acf..5c42dc4 100644
--- a/runtime/lib/mirrors_impl.dart
+++ b/runtime/lib/mirrors_impl.dart
@@ -125,17 +125,6 @@
   bool get isCurrent => true;
 
   String toString() => "IsolateMirror on '$debugName'";
-
-  Future<LibraryMirror> loadUri(Uri uri) async {
-    var result = _loadUri(uri.toString());
-    if (result == null) {
-      // Censored library.
-      throw new Exception("Cannot load $uri");
-    }
-    return result;
-  }
-
-  static LibraryMirror _loadUri(String uri) native "IsolateMirror_loadUri";
 }
 
 class _SyntheticAccessor implements MethodMirror {
diff --git a/runtime/vm/bootstrap_natives.h b/runtime/vm/bootstrap_natives.h
index 8ed4b23..b4152ff 100644
--- a/runtime/vm/bootstrap_natives.h
+++ b/runtime/vm/bootstrap_natives.h
@@ -364,7 +364,6 @@
   V(MirrorReference_equals, 2)                                                 \
   V(MirrorSystem_libraries, 0)                                                 \
   V(MirrorSystem_isolate, 0)                                                   \
-  V(IsolateMirror_loadUri, 1)                                                  \
   V(InstanceMirror_invoke, 5)                                                  \
   V(InstanceMirror_invokeGetter, 3)                                            \
   V(InstanceMirror_invokeSetter, 4)                                            \
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 88854cd..02fa964 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -791,6 +791,8 @@
   }
 }
 
+// TODO(turnidge): This clones Api::NewError.  I need to use va_copy to
+// fix this but not sure if it available on all of our builds.
 DART_EXPORT Dart_Handle Dart_NewApiError(const char* error) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
@@ -799,14 +801,6 @@
   return Api::NewHandle(T, ApiError::New(message));
 }
 
-DART_EXPORT Dart_Handle Dart_NewCompilationError(const char* error) {
-  DARTSCOPE(Thread::Current());
-  CHECK_CALLBACK_STATE(T);
-
-  const String& message = String::Handle(Z, String::New(error));
-  return Api::NewHandle(T, LanguageError::New(message));
-}
-
 DART_EXPORT Dart_Handle Dart_NewUnhandledExceptionError(Dart_Handle exception) {
   DARTSCOPE(Thread::Current());
   CHECK_CALLBACK_STATE(T);
diff --git a/sdk/lib/mirrors/mirrors.dart b/sdk/lib/mirrors/mirrors.dart
index 64f88a2..bbbb7b9 100644
--- a/sdk/lib/mirrors/mirrors.dart
+++ b/sdk/lib/mirrors/mirrors.dart
@@ -220,23 +220,6 @@
    *    reflected by [other].
    */
   bool operator ==(other);
-
-  /**
-   * Loads the library at the given uri into this isolate.
-   *
-   * WARNING: You are strongly encouraged to use Isolate.spawnUri instead when
-   * possible. IsolateMirror.loadUri should only be used when synchronous
-   * communication or shared state with dynamically loaded code is needed.
-   *
-   * If a library with the same canonicalized uri has already been loaded,
-   * the existing library will be returned. (The isolate will not load a new
-   * copy of the library.)
-   *
-   * This behavior is similar to the behavior of an import statement that
-   * appears in the root library, except that the import scope of the root
-   * library is not changed.
-   */
-  Future<LibraryMirror> loadUri(Uri uri);
 }
 
 /**
diff --git a/tests/lib_2/mirrors/dynamic_load_error.dart b/tests/lib_2/mirrors/dynamic_load_error.dart
deleted file mode 100644
index f75aaf9..0000000
--- a/tests/lib_2/mirrors/dynamic_load_error.dart
+++ /dev/null
@@ -1,6 +0,0 @@
-// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// A top-level parse error:
-import import import import
diff --git a/tests/lib_2/mirrors/dynamic_load_success.dart b/tests/lib_2/mirrors/dynamic_load_success.dart
deleted file mode 100644
index 1645a92..0000000
--- a/tests/lib_2/mirrors/dynamic_load_success.dart
+++ /dev/null
@@ -1,9 +0,0 @@
-// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-library dynamic_load_success;
-
-int _counter = 0;
-
-advanceCounter() => ++_counter;
diff --git a/tests/lib_2/mirrors/dynamic_load_test.dart b/tests/lib_2/mirrors/dynamic_load_test.dart
deleted file mode 100644
index 2cc7c3a..0000000
--- a/tests/lib_2/mirrors/dynamic_load_test.dart
+++ /dev/null
@@ -1,81 +0,0 @@
-// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import 'dart:async';
-import 'dart:mirrors';
-
-import 'package:expect/expect.dart';
-
-main() async {
-  IsolateMirror isolate = currentMirrorSystem().isolate;
-  print(isolate);
-
-  LibraryMirror success =
-      await isolate.loadUri(Uri.parse("dynamic_load_success.dart"));
-  print(success);
-  InstanceMirror result = success.invoke(#advanceCounter, []);
-  print(result);
-  Expect.equals(1, result.reflectee);
-  result = success.invoke(#advanceCounter, []);
-  print(result);
-  Expect.equals(2, result.reflectee);
-
-  LibraryMirror success2 =
-      await isolate.loadUri(Uri.parse("dynamic_load_success.dart"));
-  print(success2);
-  Expect.equals(success, success2);
-  result = success2.invoke(#advanceCounter, []);
-  print(result);
-  Expect.equals(3, result.reflectee); // Same library, same state.
-
-  LibraryMirror math = await isolate.loadUri(Uri.parse("dart:math"));
-  result = math.invoke(#max, [3, 4]);
-  print(result);
-  Expect.equals(4, result.reflectee);
-
-  Future<LibraryMirror> bad_load = isolate.loadUri(Uri.parse("DOES_NOT_EXIST"));
-  var error;
-  try {
-    await bad_load;
-  } catch (e) {
-    error = e;
-  }
-  print(error);
-  Expect.isTrue(error.toString().contains("Cannot open file") ||
-      error.toString().contains("No such file or directory"));
-  Expect.isTrue(error.toString().contains("DOES_NOT_EXIST"));
-
-  Future<LibraryMirror> bad_load2 = isolate.loadUri(Uri.parse("dart:_builtin"));
-  var error2;
-  try {
-    await bad_load2;
-  } catch (e) {
-    error2 = e;
-  }
-  print(error2);
-  Expect.isTrue(error2.toString().contains("Cannot load"));
-  Expect.isTrue(error2.toString().contains("dart:_builtin"));
-
-  // Check error is not sticky.
-  LibraryMirror success3 =
-      await isolate.loadUri(Uri.parse("dynamic_load_success.dart"));
-  print(success3);
-  Expect.equals(success, success3);
-  result = success3.invoke(#advanceCounter, []);
-  print(result);
-  Expect.equals(4, result.reflectee); // Same library, same state.
-
-  Future<LibraryMirror> bad_load3 =
-      isolate.loadUri(Uri.parse("dynamic_load_error.dart"));
-  var error3;
-  try {
-    await bad_load3;
-  } catch (e) {
-    error3 = e;
-  }
-  print(error3);
-  Expect.isTrue(error3.toString().contains("library url expected") ||
-      error3.toString().contains("Error: Expected a String"));
-  Expect.isTrue(error3.toString().contains("dynamic_load_error.dart"));
-}