Codegen support for the argument definition test.

lib/compiler/implementation/js_backend/emitter.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.
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
 class ClosureInvocationElement extends FunctionElement {
   ClosureInvocationElement(SourceString name,
                            FunctionElement other)
-      : super.from(name, other, other.enclosingElement);
+      : super.from(name, other, other.enclosingElement),
+        methodElement = other;
 
   isInstanceMember() => true;
+
+  Element getOutermostEnclosingMemberOrTopLevel() => methodElement;
+
+  /**
+   * The [member] this invocation refers to.
+   */
+  Element methodElement;
 }
 
 /**
  * Generates the code for all used classes in the program. Static fields (even
  * in classes) are ignored, since they can be treated as non-class elements.
  *
  * The code for the containing (used) methods must exist in the [:universe:].
  */
 class CodeEmitterTask extends CompilerTask {
   bool needsInheritFunction = false;
@@ skipping 299 matching lines @@
     // (4) foo$3$c(a, b, c) => foo$4(a, b, c, null);
     // (5) foo$3$d(a, b, d) => foo$4(a, b, null, d);
     // (6) foo$4$c$d(a, b, c, d) => foo$4(a, b, c, d);
     // (7) Same as (5).
     //
     // We need to generate a stub for (5) because the order of the
     // stub arguments and the real method may be different.
 
     int count = 0;
     int indexOfLastOptionalArgumentInParameters = positionalArgumentCount - 1;
+    TreeElements elements = 
+        compiler.enqueuer.resolution.getCachedElements(member);
+
     parameters.forEachParameter((Element element) {
       String jsName = JsNames.getValid(element.name.slowToString());
       if (count < positionalArgumentCount) {
         parametersBuffer[count] = jsName;
         argumentsBuffer[count] = jsName;
       } else {
         int index = names.indexOf(element.name);
         if (index != -1) {
           indexOfLastOptionalArgumentInParameters = count;
           // The order of the named arguments is not the same as the
           // one in the real method (which is in Dart source order).
           argumentsBuffer[count] = jsName;
           parametersBuffer[selector.positionalArgumentCount + index] = jsName;
+        // Note that [elements] may be null for a synthetized [member].
+        } else if (elements != null && elements.isParameterChecked(element)) {
+          CodeBuffer argumentBuffer = new CodeBuffer();
+          handler.writeConstant(argumentBuffer, SentinelConstant.SENTINEL);
+          argumentsBuffer[count] = argumentBuffer.toString();
         } else {
           Constant value = handler.initialVariableValues[element];
           if (value == null) {
             argumentsBuffer[count] = NullConstant.JsNull;
           } else {
             if (!value.isNull()) {
               // If the value is the null constant, we should not pass it
               // down to the native method.
               indexOfLastOptionalArgumentInParameters = count;
             }
@@ skipping 842 matching lines @@
         sourceName = token.slowToString();
       }
       int totalOffset = bufferOffset + offset;
       sourceMapBuilder.addMapping(
           sourceFile, token.charOffset, sourceName, totalOffset);
     });
   }
 }
 
 typedef void DefineMemberFunction(String invocationName, CodeBuffer definition);