Merge the 3 different closure nodes into a single node.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 473)
+++ runtime/vm/parser.cc	(working copy)
@@ -1123,9 +1123,7 @@
                                            AstNode* receiver) {
   Function& implicit_closure_function =
       Function::ZoneHandle(func.ImplicitClosureFunction());
-  if (receiver == NULL) {
-    return new ImplicitStaticClosureNode(token_pos, implicit_closure_function);
-  } else {
+  if (receiver != NULL) {
     // If we create an implicit instance closure from inside a closure of a
     // parameterized class, make sure that the receiver is captured as
     // instantiator.
@@ -1135,10 +1133,8 @@
         CaptureReceiver();
       }
     }
-    return new ImplicitInstanceClosureNode(token_pos,
-                                          implicit_closure_function,
-                                          receiver);
   }
+  return new ClosureNode(token_pos, implicit_closure_function, receiver, NULL);
 }
 
 
@@ -3508,7 +3504,8 @@
   // variables are not relevant for the compilation of the enclosing function.
   // This pruning is done by omitting to hook the local scope in its parent
   // scope in the constructor of LocalScope.
-  AstNode* closure = new ClosureNode(ident_pos, function, statements->scope());
+  AstNode* closure =
+      new ClosureNode(ident_pos, function, NULL, statements->scope());
 
   if (function_variable == NULL) {
     ASSERT(is_literal);