Move the dart2js snapshot into bin directory of sdk root.

sdk/lib/_internal/compiler/implementation/dart2js.dart

Index: sdk/lib/_internal/compiler/implementation/dart2js.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/dart2js.dart	(revision 21179)
+++ sdk/lib/_internal/compiler/implementation/dart2js.dart	(working copy)
@@ -20,6 +20,22 @@
 const String LIBRARY_ROOT = '../../../../..';
 const String OUTPUT_LANGUAGE_DART = 'Dart';
 
+/**
+ * A string to identify the revision or build.
+ *
+ * This ID is displayed if the compiler crashes and in verbose mode, and is
+ * an aid in reproducing bug reports.
+ *
+ * The actual string is rewritten by a wrapper script when included in the sdk.
+ */
+String BUILD_ID = 'build number could not be determined';
+
+/**
+ * Allows wrapping scripts to explicitly provide the options passed to the
+ * program instead of using the standard dart:io.
+ */
+Options OPTIONS_OVERRIDE = null;
+
 typedef void HandleOption(String option);
 
 class OptionHandler {
@@ -311,7 +327,7 @@
     sink = new CountingSink(controller);
     return sink;
   }
-
+ 
   api.compile(uri, libraryRoot, packageRoot,
               inputProvider.readStringFromUri, handler,
               options, outputProvider)
@@ -358,6 +374,7 @@
 void compilerMain(Options options) {
   var root = uriPathToNative("/$LIBRARY_ROOT");
   List<String> argv = ['--library-root=${options.script}$root'];
+  if (OPTIONS_OVERRIDE != null) options = OPTIONS_OVERRIDE;
   argv.addAll(options.arguments);
   compile(argv);
 }