RFC: Start refactoring to provide more than a single backend.

lib/compiler/implementation/emitter.dart

 // Copyright (c) 2012, 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.
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
 class ClosureInvocationElement extends FunctionElement {
   ClosureInvocationElement(SourceString name,
@@ skipping 759 matching lines @@
 };
 ''');
   }
 
   void emitExtraAccessors(Element member,
                           void defineInstanceMember(String invocationName,
                                                     String definition)) {
     if (member.kind == ElementKind.GETTER || member.kind == ElementKind.FIELD) {
       Set<Selector> selectors = compiler.universe.invokedNames[member.name];
       if (selectors !== null && !selectors.isEmpty()) {
-        compiler.emitter.emitCallStubForGetter(member, selectors,
-                                               defineInstanceMember);
+        compiler.backend.emitter.emitCallStubForGetter(
+            member, selectors, defineInstanceMember);
       }
     } else if (member.kind == ElementKind.FUNCTION) {
       if (compiler.universe.hasGetter(member, compiler)) {
-        compiler.emitter.emitDynamicFunctionGetter(member,
-                                                   defineInstanceMember);
+        compiler.backend.emitter.emitDynamicFunctionGetter(
+            member, defineInstanceMember);
       }
     }
   }
 
   void emitNoSuchMethodCalls(void defineInstanceMember(String invocationName,
                                                        String definition)) {
     // Do not generate no such method calls if there is no class.
     if (compiler.universe.instantiatedClasses.isEmpty()) return;
 
     ClassElement objectClass =
@@ skipping 183 matching lines @@
       mainBuffer.add('function init() {\n');
       mainBuffer.add('  $isolateProperties = {};\n');
       addDefineClassAndFinishClassFunctionsIfNecessary(mainBuffer);
       emitFinishIsolateConstructor(mainBuffer);
       mainBuffer.add('}\n');
       compiler.assembledCode = mainBuffer.toString();
     });
     return compiler.assembledCode;
   }
 }