Add strong mode.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 54cef6f06e10eac2958e985b728a58c1498614e5..9e9bd591b112a3cee24c911cc8ec50bca0f21ec1 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -5820,19 +5820,21 @@ void SharedFunctionInfo::set_optimization_disabled(bool disable) {
 
 
 LanguageMode SharedFunctionInfo::language_mode() {
-  STATIC_ASSERT(LANGUAGE_END == 2);
-  return BooleanBit::get(compiler_hints(), kStrictModeFunction)
-      ? STRICT : SLOPPY;
+  STATIC_ASSERT(LANGUAGE_END == 3);
+  return construct_language_mode(
+      BooleanBit::get(compiler_hints(), kStrictModeFunction),
+      BooleanBit::get(compiler_hints(), kStrongModeFunction));
 }
 
 
 void SharedFunctionInfo::set_language_mode(LanguageMode language_mode) {
-  STATIC_ASSERT(LANGUAGE_END == 2);
+  STATIC_ASSERT(LANGUAGE_END == 3);
   // We only allow language mode transitions that set the same language mode
   // again or go up in the chain:
   DCHECK(is_sloppy(this->language_mode()) || is_strict(language_mode));
   int hints = compiler_hints();
   hints = BooleanBit::set(hints, kStrictModeFunction, is_strict(language_mode));
+  hints = BooleanBit::set(hints, kStrongModeFunction, is_strong(language_mode));
   set_compiler_hints(hints);
 }