Switch dart2js to use dart 2 vm.

Change-Id: I39e807e10f53f647414d4e419b9f3ef3862bd651
Reviewed-on: https://dart-review.googlesource.com/57440
Commit-Queue: Emily Fortuna <efortuna@google.com>
Reviewed-by: Vijay Menon <vsm@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
diff --git a/sdk/bin/dart2js b/sdk/bin/dart2js
index d2e9833..9af877f 100755
--- a/sdk/bin/dart2js
+++ b/sdk/bin/dart2js
@@ -38,9 +38,10 @@
 
 case $0 in
   *_developer)
-    EXTRA_VM_OPTIONS+=('--checked')
+    EXTRA_VM_OPTIONS+=('--enable-asserts')
     ;;
 esac
+EXTRA_VM_OPTIONS+=('--preview-dart-2')
 
 # We allow extra vm options to be passed in through an environment variable.
 if [[ $DART_VM_OPTIONS ]]; then
diff --git a/sdk/bin/dart2js.bat b/sdk/bin/dart2js.bat
index c078660..3f3fd9d 100644
--- a/sdk/bin/dart2js.bat
+++ b/sdk/bin/dart2js.bat
@@ -20,10 +20,10 @@
 set DART=%BIN_DIR%\dart
 
 set EXTRA_OPTIONS=
-set EXTRA_VM_OPTIONS=
+set EXTRA_VM_OPTIONS=--preview-dart-2
 
 if _%DART2JS_DEVELOPER_MODE%_ == _1_ (
-  set EXTRA_VM_OPTIONS=%EXTRA_VM_OPTIONS% --checked
+  set EXTRA_VM_OPTIONS=%EXTRA_VM_OPTIONS% --enable-asserts
 )
 
 rem We allow extra vm options to be passed in through an environment variable.
diff --git a/sdk/bin/dart2js_sdk b/sdk/bin/dart2js_sdk
index 286859a..3896e71 100755
--- a/sdk/bin/dart2js_sdk
+++ b/sdk/bin/dart2js_sdk
@@ -45,9 +45,10 @@
 
 case $0 in
   *_developer)
-    EXTRA_VM_OPTIONS+=('--checked')
+    EXTRA_VM_OPTIONS+=('--enable-asserts')
     ;;
 esac
+EXTRA_VM_OPTIONS+=('--preview-dart-2')
 
 # We allow extra vm options to be passed in through an environment variable.
 if [[ $DART_VM_OPTIONS ]]; then
diff --git a/sdk/bin/dart2js_sdk.bat b/sdk/bin/dart2js_sdk.bat
index 9f01c0f..3b1aa66 100755
--- a/sdk/bin/dart2js_sdk.bat
+++ b/sdk/bin/dart2js_sdk.bat
@@ -21,10 +21,10 @@
 set SNAPSHOT=%BIN_DIR%\snapshots\dart2js.dart.snapshot
 
 set EXTRA_OPTIONS=
-set EXTRA_VM_OPTIONS=
+set EXTRA_VM_OPTIONS=--preview-dart-2
 
 if _%DART2JS_DEVELOPER_MODE%_ == _1_ (
-  set EXTRA_VM_OPTIONS=%EXTRA_VM_OPTIONS% --checked
+  set EXTRA_VM_OPTIONS=%EXTRA_VM_OPTIONS% --enable-asserts
 )
 
 if exist "%SNAPSHOT%" (
diff --git a/utils/compiler/BUILD.gn b/utils/compiler/BUILD.gn
index 12132aa..fbc9258 100644
--- a/utils/compiler/BUILD.gn
+++ b/utils/compiler/BUILD.gn
@@ -52,6 +52,8 @@
 }
 
 application_snapshot("dart2js") {
+  dart_version = 2
+
   deps = [
     ":compile_dart2js_platform",
     ":compile_dart2js_platform_strong",