Don't try to compile platform libraries with the new backend.

pkg/compiler/lib/src/js_backend/codegen/task.dart

 // Copyright (c) 2014, 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.
 
 /// Generate code using the cps-based IR pipeline.
 library code_generator_task;
 
 import 'glue.dart';
 import 'codegen.dart';
 import 'unsugar.dart';
@@ skipping 46 matching lines @@
   String get name => 'CPS Ir pipeline';
 
   /// Generates JavaScript code for `work.element`. First tries to use the
   /// Cps Ir -> tree ir -> js pipeline, and if that fails due to language
   /// features not implemented it will fall back to the ssa pipeline (for
   /// platform code) or will cancel compilation (for user code).
   js.Fun compile(CodegenWorkItem work) {
     types = new TypeMaskSystem(compiler);
     AstElement element = work.element;
     return compiler.withCurrentElement(element, () {
+      if (element.library.isPlatformLibrary) {
+        compiler.log('Using SSA compiler for platform element $element');
+        return fallbackCompiler.compile(work);
+      }
       try {
         if (tracer != null) {
           tracer.traceCompilation(element.name, null);
         }
         cps.FunctionDefinition cpsFunction = compileToCpsIR(element);
         cpsFunction = optimizeCpsIR(cpsFunction);
         tree_ir.FunctionDefinition treeFunction = compileToTreeIR(cpsFunction);
         treeFunction = optimizeTreeIR(treeFunction);
         return compileToJavaScript(work, treeFunction);
       } on CodegenBailout catch (e) {
-        if (element.library.isPlatformLibrary) {
-          compiler.log('Falling back to SSA compiler for $element'
-              ' (${e.message})');
-          return fallbackCompiler.compile(work);
-        } else {
-          String message = "Unable to compile $element with the new compiler.\n"
-              "  Reason: ${e.message}";
-          compiler.internalError(element, message);
-        }
+        String message = "Unable to compile $element with the new compiler.\n"
+            "  Reason: ${e.message}";
+        compiler.internalError(element, message);
       }
     });
   }
 
   void giveUp(String reason) {
     throw new CodegenBailout(null, reason);
   }
 
   void traceGraph(String title, var irObject) {
     if (tracer != null) {
@@ skipping 133 matching lines @@
       endSourcePosition =
           new TokenSourceFileLocation(sourceFile, endToken, name);
     }
     return node.withPosition(sourcePosition, endSourcePosition);
   }
 
   SourceFile sourceFileOfElement(Element element) {
     return element.implementation.compilationUnit.script.file;
   }
 }