Add JSNull, JSBool and JSFunction, and move toString into the new interceptor scheme.

sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart	(revision 15091)
+++ sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart	(working copy)
@@ -1182,7 +1182,6 @@
 
     Map<int, String> cache;
     String extraArg;
-    String extraArgWithThis;
     String extraArgWithoutComma;
     // Methods on foreign classes take an extra parameter, which is
     // the actual receiver of the call.
@@ -1190,13 +1189,11 @@
     if (backend.isInterceptorClass(member.getEnclosingClass())) {
       cache = interceptorClosureCache;
       extraArg = 'receiver, ';
-      extraArgWithThis = 'this.receiver, ';
       extraArgWithoutComma = 'receiver';
     } else {
       cache = boundClosureCache;
       extraArg = '';
       extraArgWithoutComma = '';
-      extraArgWithThis = '';
     }
 
     String closureClass =
@@ -1230,8 +1227,12 @@
       String joinedArgs = Strings.join(arguments, ", ");
       boundClosureBuffer.add(
           "$invocationName: function($joinedArgs) {");
-      boundClosureBuffer.add(
-          " return this.self[this.target]($extraArgWithThis$joinedArgs);");
+      String callArgs = extraArg.isEmpty
+          ? joinedArgs
+          : joinedArgs.isEmpty
+              ? 'this.$extraArgWithoutComma'
+              : 'this.$extraArg$joinedArgs';

[Johnni Winther, 2012/11/20 09:26:20]

Why the 'this.' prefix? 

[ngeoffray, 2012/11/20 10:30:50]

Because you're using a field of the bound closure, which is the actual receiver
of the method. For example:

var c = a.toString;
c();

The call to 'c' does not pass 'a', so when creating the bound closure for
'a.toString', you assign 'a' to a field of the bound closure. Then, when you
call the toString method you basically do:
this.self['toString'](this.receiver);

+      boundClosureBuffer.add(" return this.self[this.target]($callArgs);");

[Johnni Winther, 2012/11/20 09:26:20]

If extraArgWithoutComma is '' then callArgs becomes 'this.'. Is that
intentional?

[ngeoffray, 2012/11/20 10:30:50]

If extraArgWithoutComma is '', then extrArg is ''. Which makes callArlgs be
joinedArgs and not contain extraArgWithoutComma.

[karlklose, 2012/11/20 10:31:00]

I don't think this can happen, because extraArgWithoutComma.isEmpty ->
extraArg.isEmpty by ll. 1189-1197 and that implies callArs == joimedArgs bu l.
1231.

However, this code is really a bit complex. Can you perhaps calculate two flags
in around l. 1190 and use them down here? 

[ngeoffray, 2012/11/20 10:36:21]

I added one flag: hasExtraArgument. What other flag did upi have in mind?

[karlklose, 2012/11/20 14:06:23]

I thought about isInterceptor and hasArguments, but you could as well test for
joinedArguments.isEmpty.

       boundClosureBuffer.add(" }");
       addParameterStubs(callElement, (String stubName, CodeBuffer memberValue) {
         boundClosureBuffer.add(',\n $stubName: $memberValue');