[es6] re-implement rest parameters via desugaring

src/scopes.h

Index: src/scopes.h
diff --git a/src/scopes.h b/src/scopes.h
index 9f913450abd9f7f8622ef1b85082bd4c3e43a15b..3f791378482a31c38462f6562a308b89d7511efd 100644
--- a/src/scopes.h
+++ b/src/scopes.h
@@ -489,6 +489,17 @@ class Scope: public ZoneObject {
   // where var declarations will be hoisted to in the implementation.
   Scope* DeclarationScope();
 
+  // Find the first non-block declaration scope. This should be either a global,
+  // eval or function top scope. Used for declaring temporaries
+  Scope* TempScope() {
+    Scope* s = DeclarationScope();
+    if (s->is_block_scope()) {
+      s = s->outer_scope();

[rossberg, 2015/07/17 08:38:05]

We may potentially want to use declaration blocks in other places, too. Thus, I
would make this s->outer_scope()->DeclarationScope(), to be a bit more general;
and also remove the assert.

[caitp (gmail), 2015/07/17 15:43:23]

done in refactor

+      DCHECK(s->is_function_scope());
+    }
+    return s;
+  }
+
   Handle<ScopeInfo> GetScopeInfo(Isolate* isolate);
 
   // Get the chain of nested scopes within this scope for the source statement