Convert all symbols accessor to return read only handles so that it is not necessary to create a ne…

vm/ast.h

Index: vm/ast.h
===================================================================
--- vm/ast.h	(revision 16583)
+++ vm/ast.h	(working copy)
@@ -374,7 +374,7 @@
     ASSERT(type_.IsZoneHandle());
     ASSERT(!type_.IsNull());
     ASSERT(type_.IsFinalized());
-    ASSERT(dst_name_.IsZoneHandle());
+    ASSERT(dst_name_.IsNotTemporaryScopedHandle());
   }
 
   AstNode* expr() const { return expr_; }
@@ -448,13 +448,13 @@
  public:
   PrimaryNode(intptr_t token_pos, const Object& primary)
       : AstNode(token_pos), primary_(primary) {
-    ASSERT(primary_.IsZoneHandle());
+    ASSERT(primary_.IsNotTemporaryScopedHandle());
   }
 
   const Object& primary() const { return primary_; }
 
   bool IsSuper() const {
-    return primary().IsString() && (primary().raw() == Symbols::Super());
+    return primary().IsString() && (primary().raw() == Symbols::Super().raw());
   }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const;
@@ -1201,7 +1201,7 @@
         function_name_(function_name),
         arguments_(arguments) {
     ASSERT(receiver_ != NULL);
-    ASSERT(function_name_.IsZoneHandle());
+    ASSERT(function_name_.IsNotTemporaryScopedHandle());
     ASSERT(function_name_.IsSymbol());
     ASSERT(arguments_ != NULL);
   }
@@ -1235,7 +1235,7 @@
         receiver_(receiver),
         field_name_(field_name) {
     ASSERT(receiver_ != NULL);
-    ASSERT(field_name_.IsZoneHandle());
+    ASSERT(field_name_.IsNotTemporaryScopedHandle());
     ASSERT(field_name_.IsSymbol());
   }