fixes for angular hello: String + and disable broken arg parsing

lib/src/codegen/js_codegen.dart

Index: lib/src/codegen/js_codegen.dart
diff --git a/lib/src/codegen/js_codegen.dart b/lib/src/codegen/js_codegen.dart
index d7c1cc4c58a24725ce6ef624ae066aafd44c4e35..bb434477e1d35dbb53cc0be6f3970d6449e2579a 100644
--- a/lib/src/codegen/js_codegen.dart
+++ b/lib/src/codegen/js_codegen.dart
@@ -1447,13 +1447,12 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
   /// "extension methods". This allows types to be extended without adding
   /// extensions directly on the prototype.
   bool _isJSBuiltinType(DartType t) =>
-      rules.isNumType(t) || rules.isStringType(t) || rules.isBoolType(t);
+      typeIsPrimitiveInJS(t) || rules.isStringType(t);
 
-  bool typeIsPrimitiveInJS(DartType t) => !rules.isDynamic(t) &&
-      (rules.isIntType(t) ||
-          rules.isDoubleType(t) ||
-          rules.isBoolType(t) ||
-          rules.isNumType(t));
+  bool typeIsPrimitiveInJS(DartType t) => (rules.isIntType(t) ||

[Jacob, 2015/04/13 23:23:16]

was !rules.isDynamic(t) never needed?

[Jennifer Messerly, 2015/04/14 17:44:02]

yeah, it didn't make sense to me (how can int/double/bool/num/String be
dynamic?!). Now I'm second guessing myself. Maybe this was for the
`options.ignoreTypes` flag which generates everything as `dynamic`. if true that
means: we aren't testing the flag at all, and it was broken already in other
places.
I filed https://github.com/dart-lang/dev_compiler/issues/134 to track

+      rules.isDoubleType(t) ||
+      rules.isBoolType(t) ||
+      rules.isNumType(t));
 
   bool typeIsNonNullablePrimitiveInJS(DartType t) =>
       typeIsPrimitiveInJS(t) && rules.isNonNullableType(t);
@@ -1486,7 +1485,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
     } else if (expr is PostfixExpression) {
       type = getStaticType(expr.operand);
     }
-    if (type != null && typeIsPrimitiveInJS(type)) {
+    if (type != null && _isJSBuiltinType(type)) {
       return true;
     }
     if (expr is MethodInvocation) {
@@ -1544,7 +1543,9 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ConversionVisitor {
       return js.call(code, [_visit(left), _visit(right)]);
     }
 
-    if (binaryOperationIsPrimitive(leftType, rightType)) {
+    if (binaryOperationIsPrimitive(leftType, rightType) ||
+        rules.isStringType(leftType) && op.type == TokenType.PLUS) {
+
       // special cases where we inline the operation
       // these values are assumed to be non-null (determined by the checker)
       // TODO(jmesserly): it would be nice to just inline the method from core,