Fix issue with re-scoping in do expressions

src/parsing/parameter-initializer-rewriter.cc

Index: src/parsing/parameter-initializer-rewriter.cc
diff --git a/src/parsing/parameter-initializer-rewriter.cc b/src/parsing/parameter-initializer-rewriter.cc
index 003bbebae016562d8a4e2696b0fd4e69a0920ba1..3e3587b2bd75bcf6646bcd18635bf1a8f956d55c 100644
--- a/src/parsing/parameter-initializer-rewriter.cc
+++ b/src/parsing/parameter-initializer-rewriter.cc
@@ -62,7 +62,7 @@ void Rewriter::VisitClassLiteral(ClassLiteral* class_literal) {
 void Rewriter::VisitVariableProxy(VariableProxy* proxy) {
   if (proxy->is_resolved()) {
     Variable* var = proxy->var();
-    DCHECK_EQ(var->mode(), TEMPORARY);
+    if (var->mode() != TEMPORARY) return;

[adamk, 2016/02/29 19:20:41]

I agree that this seems fine for the ".catch" variable for now (and would also
be fine for lexical scopes). I still think there's more work to do for properly
handling var-declarations in do-expressions, but I don't think that would end up
in VisitVariableProxy (they're never eagerly-resolved anyway).

[rossberg, 2016/03/01 09:44:10]

Agreed. Var decls are the only bit missing towards full support for
do-expressions at this point, AFAICT. If I find some time, I may look into that.

     if (old_scope_->RemoveTemporary(var)) {
       var->set_scope(new_scope_);
       new_scope_->AddTemporary(var);