Eagerly extract stack limit from Isolate in InitializeAstVisitor()

src/full-codegen/full-codegen.h

Index: src/full-codegen/full-codegen.h
diff --git a/src/full-codegen/full-codegen.h b/src/full-codegen/full-codegen.h
index 8b4e89fa037cb6b4954d36773f072d5734d2afa3..abe982569ab3da19f289568a025e16ea1b45094e 100644
--- a/src/full-codegen/full-codegen.h
+++ b/src/full-codegen/full-codegen.h
@@ -688,6 +688,7 @@ class FullCodeGenerator: public AstVisitor {
   const ExpressionContext* context() { return context_; }
   void set_new_context(const ExpressionContext* context) { context_ = context; }
 
+  Isolate* isolate() const { return info_->isolate(); }
   Handle<Script> script() { return info_->script(); }
   bool is_eval() { return info_->is_eval(); }
   bool is_native() { return info_->is_native(); }