Add support for compiling Dart via the FE in dart2js.

pkg/compiler/lib/src/ssa/type_builder.dart

 // Copyright (c) 2016, 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 'graph_builder.dart';
 import 'nodes.dart';
 import '../closure.dart';
 import '../common.dart';
 import '../types/types.dart';
 import '../elements/elements.dart';
@@ skipping 147 matching lines @@
         TypeInfoExpressionKind.INSTANCE,
         builder.closedWorld.elementEnvironment.getThisType(interface.element),
         inputs,
         builder.commonMasks.dynamicType);
     return representation;
   }
 
   /// Check that [type] is valid in the context of `localsHandler.contextClass`.
   /// This should only be called in assertions.
   bool assertTypeInContext(DartType type, [Spannable spannable]) {
-    if (builder.compiler.options.useKernel) return true;
-    if (builder.compiler.options.loadFromDill) return true;
+    if (builder.compiler.options.useKernelInSsa) return true;
     ClassEntity contextClass = DartTypes.getClassContext(type);
     assert(
         contextClass == null ||
             contextClass == builder.localsHandler.contextClass,
         failedAt(
             spannable ?? CURRENT_ELEMENT_SPANNABLE,
             "Type '$type' is not valid context of "
             "${builder.localsHandler.contextClass}."));
     return true;
   }
@@ skipping 86 matching lines @@
           analyzeTypeArgument(type, builder.sourceElement);
       // TypeMasks don't encode function types.
       TypeMask refinedMask = original.instructionType;
       return new HTypeConversion.withTypeRepresentation(
           type, kind, refinedMask, original, reifiedType);
     } else {
       return original.convertType(builder.closedWorld, type, kind);
     }
   }
 }