Revert "Use an explicit 'this' parameter instead of 'This' nodes."

pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
index d16fd8c84ed136bb8520ef030f4740f142b60ddb..1510315ede7eaabeb732eeebadcf722b4dd8ab3a 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart
@@ -638,6 +638,12 @@ class Constant extends Primitive {
   accept(Visitor visitor) => visitor.visitConstant(this);
 }
 
+class This extends Primitive {
+  This();
+
+  accept(Visitor visitor) => visitor.visitThis(this);
+}
+
 /// Reify the given type variable as a [Type].
 /// This depends on the current binding of 'this'.
 class ReifyTypeVar extends Primitive implements DartSpecificNode {
@@ -700,8 +706,6 @@ class Parameter extends Primitive {
   int parentIndex;
 
   accept(Visitor visitor) => visitor.visitParameter(this);
-
-  String toString() => 'Parameter(${hint == null ? null : hint.name})';
 }
 
 /// Continuations are normally bound by 'let cont'.  A continuation with one
@@ -793,7 +797,6 @@ class RunnableBody extends InteriorNode {
 class FunctionDefinition extends Node
     implements ExecutableDefinition {
   final FunctionElement element;
-  final Parameter thisParameter;
   /// Mixed list of [Parameter]s and [MutableVariable]s.
   final List<Definition> parameters;
   final RunnableBody body;
@@ -803,14 +806,12 @@ class FunctionDefinition extends Node
   final List<ConstantExpression> defaultParameterValues;
 
   FunctionDefinition(this.element,
-      this.thisParameter,
       this.parameters,
       this.body,
       this.localConstants,
       this.defaultParameterValues);
 
   FunctionDefinition.abstract(this.element,
-                              this.thisParameter,
                               this.parameters,
                               this.defaultParameterValues)
       : body = null,
@@ -847,14 +848,13 @@ class ConstructorDefinition extends FunctionDefinition {
   final List<Initializer> initializers;
 
   ConstructorDefinition(ConstructorElement element,
-                        Definition thisParameter, // only Dart
                         List<Definition> parameters,
                         RunnableBody body,
                         this.initializers,
                         List<ConstDeclaration> localConstants,
                         List<ConstantExpression> defaultParameterValues)
-  : super(element, thisParameter, parameters, body, localConstants,
-          defaultParameterValues);
+      : super(element, parameters, body, localConstants,
+              defaultParameterValues);
 
   // 'Abstract' here means "has no body" and is used to represent external
   // constructors.
@@ -863,7 +863,7 @@ class ConstructorDefinition extends FunctionDefinition {
       List<Definition> parameters,
       List<ConstantExpression> defaultParameterValues)
       : initializers = null,
-        super.abstract(element, null, parameters, defaultParameterValues);
+        super.abstract(element, parameters, defaultParameterValues);
 
   accept(Visitor visitor) => visitor.visitConstructorDefinition(this);
   applyPass(Pass pass) => pass.rewriteConstructorDefinition(this);
@@ -937,6 +937,7 @@ abstract class Visitor<T> {
   T visitLiteralList(LiteralList node);
   T visitLiteralMap(LiteralMap node);
   T visitConstant(Constant node);
+  T visitThis(This node);
   T visitReifyTypeVar(ReifyTypeVar node);
   T visitCreateFunction(CreateFunction node);
   T visitGetMutableVariable(GetMutableVariable node);
@@ -989,7 +990,6 @@ class RecursiveVisitor implements Visitor {
   processFunctionDefinition(FunctionDefinition node) {}
   visitFunctionDefinition(FunctionDefinition node) {
     processFunctionDefinition(node);
-    if (node.thisParameter != null) visit(node.thisParameter);
     node.parameters.forEach(visit);
     if (!node.isAbstract) {
       visit(node.body);
@@ -999,7 +999,6 @@ class RecursiveVisitor implements Visitor {
   processConstructorDefinition(ConstructorDefinition node) {}
   visitConstructorDefinition(ConstructorDefinition node) {
     processConstructorDefinition(node);
-    if (node.thisParameter != null) visit(node.thisParameter);
     node.parameters.forEach(visit);
     node.initializers.forEach(visit);
     visit(node.body);
@@ -1143,6 +1142,9 @@ class RecursiveVisitor implements Visitor {
   processConstant(Constant node) {}
   visitConstant(Constant node) => processConstant(node);
 
+  processThis(This node) {}
+  visitThis(This node) => processThis(node);
+
   processReifyTypeVar(ReifyTypeVar node) {}
   visitReifyTypeVar(ReifyTypeVar node) => processReifyTypeVar(node);
 
@@ -1419,6 +1421,9 @@ class RegisterAllocator implements Visitor {
   void visitConstant(Constant node) {
   }
 
+  void visitThis(This node) {
+  }
+
   void visitReifyTypeVar(ReifyTypeVar node) {
   }