dart2js: Let the emitter generate the program.

pkg/compiler/lib/src/js_emitter/code_emitter_task.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.
 
 part of dart2js.js_emitter;
 
 const USE_NEW_EMITTER = const bool.fromEnvironment("dart2js.use.new.emitter");
 
 /**
  * Generates the code for all used classes in the program. Static fields (even
@@ skipping 397 matching lines @@
     computeNeededStaticNonFinalFields();
     computeNeededLibraries();
   }
 
   int assembleProgram() {
     return measure(() {
       emitter.invalidateCaches();
 
       computeAllNeededEntities();
 
-      Program program =
-          new ProgramBuilder(compiler, namer, this).buildProgram();
-      return emitter.emitProgram(program);
+      ProgramBuilder programBuilder = new ProgramBuilder(compiler, namer, this);
+      return emitter.emitProgram(programBuilder);
     });
   }
 }
 
 abstract class Emitter {
-  /// Emits [program] and returns the size of the generated output.
-  int emitProgram(Program program);
+  /// Uses the [programBuilder] to generate a model of the program, emits
+  /// the program, and returns the size of the generated output.
+  int emitProgram(ProgramBuilder programBuilder);
 
   /// Returns the JS function that must be invoked to get the value of the
   /// lazily initialized static.
   jsAst.Expression isolateLazyInitializerAccess(FieldElement element);
 
   /// Returns the closure expression of a static function.
   jsAst.Expression isolateStaticClosureAccess(FunctionElement element);
 
   /// Returns the JS code for accessing the embedded [global].
   jsAst.Expression generateEmbeddedGlobalAccess(String global);
@@ skipping 26 matching lines @@
   jsAst.Expression closureClassConstructorAccess(ClosureClassElement e);
 
   /// Returns the JS expression representing a function that returns 'null'
   jsAst.Expression generateFunctionThatReturnsNull();
 
   int compareConstants(ConstantValue a, ConstantValue b);
   bool isConstantInlinedOrAlreadyEmitted(ConstantValue constant);
 
   void invalidateCaches();
 }