Remove the global Strength enum class completely.

src/runtime/runtime.h

 // 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.
 
 #ifndef V8_RUNTIME_RUNTIME_H_
 #define V8_RUNTIME_RUNTIME_H_
 
 #include "src/allocation.h"
 #include "src/base/platform/time.h"
 #include "src/objects.h"
@@ skipping 411 matching lines @@
   F(LoadMutableDouble, 2, 1)                         \
   F(TryMigrateInstance, 1, 1)                        \
   F(IsJSGlobalProxy, 1, 1)                           \
   F(DefineAccessorPropertyUnchecked, 5, 1)           \
   F(DefineDataPropertyUnchecked, 4, 1)               \
   F(DefineDataPropertyInLiteral, 5, 1)               \
   F(GetDataProperty, 2, 1)                           \
   F(HasFastPackedElements, 1, 1)                     \
   F(ValueOf, 1, 1)                                   \
   F(IsJSReceiver, 1, 1)                              \
-  F(IsStrong, 1, 1)                                  \
   F(ClassOf, 1, 1)                                   \
   F(DefineGetterPropertyUnchecked, 4, 1)             \
   F(DefineSetterPropertyUnchecked, 4, 1)             \
   F(ToObject, 1, 1)                                  \
   F(ToPrimitive, 1, 1)                               \
   F(ToPrimitive_Number, 1, 1)                        \
   F(ToPrimitive_String, 1, 1)                        \
   F(ToNumber, 1, 1)                                  \
   F(ToInteger, 1, 1)                                 \
   F(ToLength, 1, 1)                                  \
@@ skipping 746 matching lines @@
 
 class DeclareGlobalsEvalFlag : public BitField<bool, 0, 1> {};
 class DeclareGlobalsNativeFlag : public BitField<bool, 1, 1> {};
 STATIC_ASSERT(LANGUAGE_END == 3);
 class DeclareGlobalsLanguageMode : public BitField<LanguageMode, 2, 2> {};
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_RUNTIME_RUNTIME_H_