cps2js: Clean up some obsolete TODOs.

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

 // Copyright (c) 2014, 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.
 
 library code_generator;
 
 import 'glue.dart';
 
 import '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../js/js.dart' as js;
@@ skipping 77 matching lines @@
     js.Expression result = node.accept(this);
     if (result == null) {
       glue.reportInternalError('$node did not produce code.');
     }
     return result;
   }
 
   /// Generates a name for the given variable. First trying with the name of
   /// the [Variable.element] if it is non-null.
   String getVariableName(tree_ir.Variable variable) {
-    // TODO(sigurdm): Handle case where the variable belongs to an enclosing
-    // function.
-    if (variable.host != currentFunction) giveup(variable);
+    // Functions are not nested in the JS backend.
+    assert(variable.host == currentFunction);
 
     // Get the name if we already have one.
     String name = variableNames[variable];
     if (name != null) {
       return name;
     }
 
     // Synthesize a variable name that isn't used elsewhere.
     // The [usedVariableNames] set is shared between nested emitters,
     // so this also prevents clash with variables in an enclosing/inner scope.
@@ skipping 58 matching lines @@
   js.Expression buildConstant(ConstantValue constant) {
     registry.registerCompileTimeConstant(constant);
     return glue.constantReference(constant);
   }
 
   @override
   js.Expression visitConstant(tree_ir.Constant node) {
     return buildConstant(node.expression.value);
   }
 
-  @override
-  js.Expression visitFunctionExpression(tree_ir.FunctionExpression node) {
-    return giveup(node);
-    // TODO: implement visitFunctionExpression
-  }
-
   js.Expression compileConstant(ParameterElement parameter) {
     return buildConstant(glue.getConstantForVariable(parameter).value);
   }
 
   // TODO(karlklose): get rid of the selector argument.
   js.Expression buildStaticInvoke(Selector selector,
                                   Element target,
                                   List<js.Expression> arguments) {
     registry.registerStaticInvocation(target.declaration);
     if (target == glue.getInterceptorMethod) {
@@ skipping 140 matching lines @@
   }
 
   @override
   js.Expression visitReifyTypeVar(tree_ir.ReifyTypeVar node) {
     return giveup(node);
     // TODO: implement visitReifyTypeVar
   }
 
   @override
   js.Expression visitThis(tree_ir.This node) {
-    // TODO(sigurdm): Inside a js closure this will not work.
     return new js.This();
   }
 
   @override
   js.Expression visitTypeOperator(tree_ir.TypeOperator node) {
     return giveup(node);
     // TODO: implement visitTypeOperator
   }
 
   @override
@@ skipping 16 matching lines @@
   }
 
   @override
   void visitExpressionStatement(tree_ir.ExpressionStatement node) {
     accumulator.add(new js.ExpressionStatement(
         visitExpression(node.expression)));
     visitStatement(node.next);
   }
 
   @override
-  void visitFunctionDeclaration(tree_ir.FunctionDeclaration node) {
-    giveup(node);
-    // TODO: implement visitFunctionDeclaration
-  }
-
-  @override
   void visitIf(tree_ir.If node) {
     accumulator.add(new js.If(visitExpression(node.condition),
                               buildBody(node.thenStatement),
                               buildBody(node.elseStatement)));
   }
 
   @override
   void visitLabeledStatement(tree_ir.LabeledStatement node) {
     accumulator.add(buildLabeled(() => buildBody(node.body),
                                  node.label,
@@ skipping 84 matching lines @@
     accumulator.add(
         buildWhile(new js.LiteralBool(true), node.body, node.label, node));
   }
 
   @override
   void visitReturn(tree_ir.Return node) {
     accumulator.add(new js.Return(visitExpression(node.value)));
   }
 
   @override
-  js.Expression visitFieldInitializer(tree_ir.FieldInitializer node) {
-    return giveup(node);
-    // TODO: implement FieldInitializer
-  }
-
-  @override
-  js.Expression visitSuperInitializer(tree_ir.SuperInitializer node) {
-    return giveup(node);
-    // TODO: implement SuperInitializer
-  }
-
-  @override
   js.Expression visitCreateBox(tree_ir.CreateBox node) {
     return new js.ObjectInitializer([]);
   }
 
   @override
   js.Expression visitCreateInstance(tree_ir.CreateInstance node) {
     registry.registerInstantiatedClass(node.classElement);
     return new js.New(glue.constructorAccess(node.classElement),
                       node.arguments.map(visitExpression).toList());
   }
 
   @override
   js.Expression visitGetField(tree_ir.GetField node) {
     return new js.PropertyAccess.field(
         visitExpression(node.object),
         glue.instanceFieldPropertyName(node.field));
   }
 
   @override
   void visitSetField(tree_ir.SetField node) {
     js.PropertyAccess field =
         new js.PropertyAccess.field(
             visitExpression(node.object),
             glue.instanceFieldPropertyName(node.field));
     js.Assignment asn = new js.Assignment(field, visitExpression(node.value));
     accumulator.add(new js.ExpressionStatement(asn));
     visitStatement(node.next);
   }
+
+  // Dart-specific IR nodes
+
+  @override
+  visitFunctionExpression(tree_ir.FunctionExpression node) {
+    return errorUnsupportedNode(node);
+  }
+
+  @override
+  visitFunctionDeclaration(tree_ir.FunctionDeclaration node) {
+    return errorUnsupportedNode(node);
+  }
+
+  @override
+  visitFieldInitializer(tree_ir.FieldInitializer node) {
+    return errorUnsupportedNode(node);
+  }
+
+  @override
+  visitSuperInitializer(tree_ir.SuperInitializer node) {
+    return errorUnsupportedNode(node);
+  }
+
+  dynamic errorUnsupportedNode(tree_ir.DartSpecificNode node) {
+    throw "Unsupported node in JS backend: $node";
+  }
 }