dart2js: Move parameterStub generation to parameter_stub_generator and add parameter stubs to model.

pkg/compiler/lib/src/js_emitter/program_builder.dart

Index: pkg/compiler/lib/src/js_emitter/program_builder.dart
diff --git a/pkg/compiler/lib/src/js_emitter/program_builder.dart b/pkg/compiler/lib/src/js_emitter/program_builder.dart
index 01c38363c652c425b6f3f54251a396ed2a68a335..6bd551b25f4f9970018100f78c61550d6613e4f0 100644
--- a/pkg/compiler/lib/src/js_emitter/program_builder.dart
+++ b/pkg/compiler/lib/src/js_emitter/program_builder.dart
@@ -19,6 +19,7 @@ import 'js_emitter.dart' show
     ClassStubGenerator,
     CodeEmitterTask,
     InterceptorStubGenerator,
+    ParameterStubGenerator,
     TypeTestGenerator,
     TypeTestProperties;
 
@@ -424,7 +425,6 @@ class ProgramBuilder {
     bool isClosure = false;
     bool isNotApplyTarget = !element.isFunction || element.isAccessor;
 
-    final bool needsStubs = _methodNeedsStubs(element);
     final bool canBeReflected = _methodCanBeReflected(element);
     final bool canBeApplied = _methodCanBeApplied(element);
     final bool hasSuperAlias = backend.isAliasedSuperMember(element);
@@ -454,7 +454,27 @@ class ProgramBuilder {
     return new InstanceMethod(element, name, code, needsTearOff: canTearOff,
         tearOffName: tearOffName, isClosure: isClosure,
         hasSuperAlias: hasSuperAlias, canBeApplied: canBeApplied,
-        canBeReflected: canBeReflected, needsStubs: needsStubs);
+        canBeReflected: canBeReflected,
+        parameterStubs: _generateParameterStubs(element, canTearOff));
+  }
+
+  List<ParameterStubMethod> _generateParameterStubs(FunctionElement element,
+                                           bool canTearOff) {
+    List<ParameterStubMethod> parameterStubs = <ParameterStubMethod>[];

[herhut, 2015/01/30 10:02:22]

How about 

if (!_methodNeedsStubs) return const <ParameterStubMethod>[];

I think it makes it more obvious that nothing happens unless a method needs
stubs. 

[zarah, 2015/01/30 12:46:39]

Done.

+      if (_methodNeedsStubs(element)) {
+        ParameterStubGenerator generator =
+            new ParameterStubGenerator(_compiler, namer, backend);
+        Map<Selector, js.Expression> parameterStubsForElement =
+            generator.generateParameterStubs(element, canTearOff);
+        parameterStubsForElement.forEach((Selector selector,
+                                          js.Expression code) {
+          String name = namer.invocationName(selector);
+          parameterStubs.add(
+              _buildParameterStubMethod(name, code, selector,
+                                        element: element));
+        });
+      }
+      return parameterStubs;
   }
 
   /// Builds a stub method.
@@ -466,6 +486,12 @@ class ProgramBuilder {
     return new StubMethod(name, code, element: element);
   }
 
+  Method _buildParameterStubMethod(String name, js.Expression code,
+                                   Selector selector,
+                                   {Element element}) {
+    return new ParameterStubMethod(name, code, selector, element: element);
+  }
+
   // The getInterceptor methods directly access the prototype of classes.
   // We must evaluate these classes eagerly so that the prototype is
   // accessible.
@@ -563,7 +589,6 @@ class ProgramBuilder {
     js.Expression code = backend.generatedCode[element];
 
     final bool isNotApplyTarget = !element.isConstructor && !element.isAccessor;
-    final bool needsStubs = _methodNeedsStubs(element);
     final bool canBeApplied = _methodCanBeApplied(element);
     final bool canBeReflected = _methodCanBeReflected(element);
 
@@ -579,7 +604,9 @@ class ProgramBuilder {
                                 tearOffName: tearOffName,
                                 canBeApplied: canBeApplied,
                                 canBeReflected: canBeReflected,
-                                needsStubs: needsStubs);
+                                parameterStubs:
+                                    _generateParameterStubs(element,
+                                                            needsTearOff));
   }
 
   void _registerConstants(OutputUnit outputUnit,