dart2js: Refactor how parameter stubs are handled.

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

Index: pkg/compiler/lib/src/js_emitter/model.dart
diff --git a/pkg/compiler/lib/src/js_emitter/model.dart b/pkg/compiler/lib/src/js_emitter/model.dart
index 9b782382a38ea38088330060dfc74b8d43196487..168a44b33ecd942fad8cec90f0707f4ec8f6c550 100644
--- a/pkg/compiler/lib/src/js_emitter/model.dart
+++ b/pkg/compiler/lib/src/js_emitter/model.dart
@@ -327,9 +327,7 @@ abstract class Method {
   Method(this.element, this.name, this.code);
 }
 
-/**
- * A method that corresponds to a method in the original Dart program.
- */
+/// A method that corresponds to a method in the original Dart program.
 class DartMethod extends Method {
   final bool needsTearOff;
   final String tearOffName;
@@ -338,15 +336,19 @@ class DartMethod extends Method {
   final bool canBeApplied;
   final bool canBeReflected;
 
+  // If this method can be torn off, contains the name of the corresponding
+  // call method. For example, for the member `foo$1$name` it would be
+  // `call$1$name` (in unminified mode).
+  final String callName;
+
   DartMethod(Element element, String name, js.Expression code,
-             this.parameterStubs,
+             this.parameterStubs, this.callName,
              {this.needsTearOff, this.tearOffName, this.canBeApplied,
              this.canBeReflected})
       : super(element, name, code) {
     assert(needsTearOff != null);
     assert(!needsTearOff || tearOffName != null);
     assert(canBeApplied != null);
-    assert(parameterStubs != null);
     assert(canBeReflected != null);
   }
 }
@@ -356,14 +358,16 @@ class InstanceMethod extends DartMethod {
   final bool hasSuperAlias;
   final bool isClosure;
 
-  InstanceMethod(element, name, code, List<ParameterStubMethod> parameterStubs,
-      {bool needsTearOff,
-       String tearOffName,
-       this.hasSuperAlias,
-       bool canBeApplied,
-       bool canBeReflected,
+  InstanceMethod(Element element, String name, js.Expression code,
+                 List<ParameterStubMethod> parameterStubs,
+                 String callName,
+                 {bool needsTearOff,
+                  String tearOffName,
+                  this.hasSuperAlias,
+                  bool canBeApplied,
+                  bool canBeReflected,
        this.isClosure})
-      : super(element, name, code, parameterStubs,
+      : super(element, name, code, parameterStubs, callName,
               needsTearOff: needsTearOff,
               tearOffName: tearOffName,
               canBeApplied: canBeApplied,
@@ -373,28 +377,34 @@ class InstanceMethod extends DartMethod {
   }
 }
 
-/**
- * A method that is generated by the backend and has not direct correspondence
- * to a method in the original Dart program. Examples are getter and setter
- * stubs and stubs to dispatch calls to methods with optional parameters.
- */
+/// A method that is generated by the backend and has not direct correspondence
+/// to a method in the original Dart program. Examples are getter and setter
+/// stubs and stubs to dispatch calls to methods with optional parameters.
 class StubMethod extends Method {
   StubMethod(String name, js.Expression code,
              {Element element})
       : super(element, name, code);
 }
 
- /// A method that is generated for the different versions of method calls of
- /// methods with named parameters,
- ///
- /// For example, for a method foo(a, b, {c, d}) that is called as
- /// foo(1, 2, c: 3), we have the stub
- /// foo$3$c(a, b, c) => foo$4$c$d(a, b, c, null);
+/// A stub that adapts and redirects to the main method (the one containing)
+/// the actual code.
+///
+/// For example, given a method `foo$2(x, [y: 499])` a possible parameter
+/// stub-method could be `foo$1(x) => foo$2(x, 499)`.
+///
+/// ParameterStubMethods are always attached to (static or instance) methods.
 class ParameterStubMethod extends StubMethod {
-  final Selector selector;
-  ParameterStubMethod(String name, js.Expression code, this.selector,
-                     {Element element})
-       : super(name, code, element: element);
+  /// The `call` name of this stub.
+  ///
+  /// When an instance method is torn off, it is invoked as a `call` member and
+  /// not it's original name anymore. The [callName] provides the stub's
+  /// name when it is used this way.
+  ///
+  /// If a stub's member can not be torn off, the [callName] is `null`.
+  String callName;
+
+  ParameterStubMethod(String name, this.callName, js.Expression code)
+      : super(name, code);
 }
 
 abstract class StaticMethod implements Method {
@@ -405,10 +415,11 @@ class StaticDartMethod extends DartMethod implements StaticMethod {
   final Holder holder;
 
   StaticDartMethod(Element element, String name, this.holder,
-                   js.Expression code, parameterStubs,
+                   js.Expression code, List<ParameterStubMethod> parameterStubs,
+                   String callName,
                    {bool needsTearOff, String tearOffName, bool canBeApplied,
                     bool canBeReflected})
-      : super(element, name, code, parameterStubs,
+      : super(element, name, code, parameterStubs, callName,
               needsTearOff: needsTearOff,
               tearOffName : tearOffName,
               canBeApplied : canBeApplied,