Strawman: check strong mode free variables against the global object.

src/pending-compilation-error-handler.h

Index: src/pending-compilation-error-handler.h
diff --git a/src/pending-compilation-error-handler.h b/src/pending-compilation-error-handler.h
index 60923d649d9c60677ba918b130a62f68dbda2769..c75f23d0394f3be362b132d1d24e70ac6f105030 100644
--- a/src/pending-compilation-error-handler.h
+++ b/src/pending-compilation-error-handler.h
@@ -7,13 +7,12 @@
 
 #include "src/base/macros.h"
 #include "src/globals.h"
+#include "src/handles.h"
 
 namespace v8 {
 namespace internal {
 
 class AstRawString;
-template <class T>
-class Handle;
 class Isolate;
 class Script;
 
@@ -56,6 +55,20 @@ class PendingCompilationErrorHandler {
     error_type_ = error_type;
   }
 
+  void ReportMessageAt(int start_position, int end_position,
+                       const char* message, Handle<String> arg,
+                       ParseErrorType error_type = kSyntaxError) {
+    if (has_pending_error_) return;
+    has_pending_error_ = true;
+    start_position_ = start_position;
+    end_position_ = end_position;
+    message_ = message;
+    char_arg_ = nullptr;
+    arg_ = nullptr;
+    handle_arg_ = arg;
+    error_type_ = error_type;
+  }
+
   bool has_pending_error() const { return has_pending_error_; }
 
   void ThrowPendingError(Isolate* isolate, Handle<Script> script);
@@ -67,6 +80,7 @@ class PendingCompilationErrorHandler {
   const char* message_;
   const AstRawString* arg_;
   const char* char_arg_;
+  Handle<String> handle_arg_;
   ParseErrorType error_type_;
 
   DISALLOW_COPY_AND_ASSIGN(PendingCompilationErrorHandler);