Remove JavaSystem from java_core.

It is not used internally at all.

R=brianwilkerson@google.com
BUG=

Review URL: https://codereview.chromium.org/2324893003 .
diff --git a/pkg/analyzer/lib/src/generated/java_core.dart b/pkg/analyzer/lib/src/generated/java_core.dart
index 59e904e..074bb3c 100644
--- a/pkg/analyzer/lib/src/generated/java_core.dart
+++ b/pkg/analyzer/lib/src/generated/java_core.dart
@@ -4,8 +4,6 @@
 
 library analyzer.src.generated.java_core;
 
-final Stopwatch nanoTimeStopwatch = new Stopwatch();
-
 /**
  * Inserts the given arguments into [pattern].
  *
@@ -202,19 +200,6 @@
   }
 }
 
-class JavaSystem {
-  static int currentTimeMillis() {
-    return (new DateTime.now()).millisecondsSinceEpoch;
-  }
-
-  static int nanoTime() {
-    if (!nanoTimeStopwatch.isRunning) {
-      nanoTimeStopwatch.start();
-    }
-    return nanoTimeStopwatch.elapsedMicroseconds * 1000;
-  }
-}
-
 class PrintStringWriter extends PrintWriter {
   final StringBuffer _sb = new StringBuffer();
 
diff --git a/pkg/analyzer/lib/src/generated/source.dart b/pkg/analyzer/lib/src/generated/source.dart
index 41f6c88..2fc6c2d 100644
--- a/pkg/analyzer/lib/src/generated/source.dart
+++ b/pkg/analyzer/lib/src/generated/source.dart
@@ -42,6 +42,8 @@
    */
   HashMap<String, int> _stampMap = new HashMap<String, int>();
 
+  int _nextStamp = 0;
+
   /**
    * Visit all entries of this cache.
    */
@@ -82,7 +84,7 @@
       _stampMap.remove(fullName);
       return _contentMap.remove(fullName);
     } else {
-      int newStamp = JavaSystem.currentTimeMillis();
+      int newStamp = _nextStamp++;
       int oldStamp = _stampMap[fullName];
       _stampMap[fullName] = newStamp;
       // Occasionally, if this method is called in rapid succession, the
diff --git a/pkg/analyzer/test/src/dart/element/element_test.dart b/pkg/analyzer/test/src/dart/element/element_test.dart
index 72aae14..6bc35ef 100644
--- a/pkg/analyzer/test/src/dart/element/element_test.dart
+++ b/pkg/analyzer/test/src/dart/element/element_test.dart
@@ -13,7 +13,6 @@
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisOptionsImpl;
-import 'package:analyzer/src/generated/java_core.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:analyzer/src/generated/testing/ast_factory.dart';
 import 'package:analyzer/src/generated/testing/element_factory.dart';
@@ -3942,10 +3941,10 @@
     LibraryElement library = ElementFactory.library(context, "foo");
     context.setContents(library.definingCompilationUnit.source, "sdfsdff");
     // Assert that we are not up to date if the target has an old time stamp.
-    expect(library.isUpToDate(0), isFalse);
+    expect(library.isUpToDate(-1), isFalse);
     // Assert that we are up to date with a target modification time in the
     // future.
-    expect(library.isUpToDate(JavaSystem.currentTimeMillis() + 1000), isTrue);
+    expect(library.isUpToDate(1 << 33), isTrue);
   }
 
   void test_setImports() {