Introduce LanguageMode, drop StrictMode.

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/v8.h"
@@ skipping 386 matching lines @@
       }
       DCHECK(cursor + 4 <= elements->length());
 
       Handle<Code> code = frames[i].code();
       Handle<Smi> offset(Smi::FromInt(frames[i].offset()), this);
       // The stack trace API should not expose receivers and function
       // objects on frames deeper than the top-most one with a strict
       // mode function.  The number of sloppy frames is stored as
       // first element in the result array.
       if (!encountered_strict_function) {
-        if (fun->shared()->strict_mode() == STRICT) {
+        if (is_strict(fun->shared()->language_mode())) {
           encountered_strict_function = true;
         } else {
           sloppy_frames++;
         }
       }
       elements->set(cursor++, *recv);
       elements->set(cursor++, *fun);
       elements->set(cursor++, *code);
       elements->set(cursor++, *offset);
       frames_seen++;
@@ skipping 2167 matching lines @@
   if (prev_ && prev_->Intercept(flag)) return true;
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 } }  // namespace v8::internal