Remove the type token used to pass element information to arrays.

compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java

Index: compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java
diff --git a/compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java b/compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java
index 87ae13592b62927c983f588aeb5f2ec2b3fdcd55..d3c552f073b812207f54ca2a5ff07acdb1b4a5b6 100644
--- a/compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java
+++ b/compiler/java/com/google/dart/compiler/backend/js/GenerateJavascriptAST.java
@@ -1037,9 +1037,11 @@ public class GenerateJavascriptAST {
       // Add the arguments to the constructor invocation. Note that the constructor call is still
       // missing the 'tmp' variable. We will add it later.
       List<DartParameter> params = x.getFunction().getParams();
+      List<JsName> jsArgNames = new ArrayList<JsName>();
       for (DartParameter p : params) {
         // TODO(ngeoffray): We should actually copy the arguments. See b/4424659.
         JsName argName = getJsName(p.getNormalizedNode().getSymbol());
+        jsArgNames.add(argName);
         constructorInvocation.getArguments().add(argName.makeRef());
       }
 
@@ -1058,6 +1060,12 @@ public class GenerateJavascriptAST {
         addInitializers(x, factoryFunction, tempVar);
         rtt.maybeAddClassRuntimeTypeToConstructor(classElement, factoryFunction, tempVar.makeRef());
         JsNew jsNew = new JsNew(curClassJsName.makeRef());
+        if (classElement.getNativeName() != null && x.getFunction().getBody() == null) {

[floitsch, 2012/01/16 13:23:26]

I don't understand this code. (In any case add comments).

[mmendez, 2012/01/17 12:48:04]

Added a comment in the code to match the comment in the code review description.

For native classes that declare a body-less constructor, we will pass the
factory arguments to the native "new" expression.

In this case, it causes the length of the array to be passed to the "new
Array..." JS expression being generated which allows us to use the generated
factory method for instantiating the native class as well as optionally adding
the runtime type information if necessary without a temporary object.
 
On 2012/01/16 13:23:26, floitsch wrote:

+          List<JsExpression> newArguments = jsNew.getArguments();
+          for (JsName jsArgName : jsArgNames) {
+            newArguments.add(jsArgName.makeRef());
+          }
+        }
         factoryFunction.getBody().getStatements().add(0, AstUtil.newVar(x, tempVar, jsNew));
       }