Properly thread language mode to compilation cache

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index a2560e4c3b1062c6372f94c71f50cad87e35996e..953a37519e4ba4b784606d699e2a42c62bbc58c4 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -840,10 +840,6 @@ void Shell::AddHistogramSample(void* histogram, int sample) {
 
 void Shell::InstallUtilityScript(Isolate* isolate) {
   HandleScope scope(isolate);
-  // TODO(rossberg): Utility scripts do not yet obey strong mode rules.
-  bool use_strong = i::FLAG_use_strong;
-  i::FLAG_use_strong = false;
-
   // If we use the utility context, we have to set the security tokens so that
   // utility, evaluation and debug context can all access each other.
   v8::Local<v8::Context> utility_context =
@@ -893,8 +889,6 @@ void Shell::InstallUtilityScript(Isolate* isolate) {
 
   // Start the in-process debugger if requested.
   if (i::FLAG_debugger) v8::Debug::SetDebugEventListener(HandleDebugEvent);
-
-  i::FLAG_use_strong = use_strong;
 }
 #endif  // !V8_SHARED