Remove --experimental-classes flag and related dead code.

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/objects.h"
 #include "src/zone.h"
@@ skipping 169 matching lines @@
   /* Numbers */                                            \
   F(NumberToRadixString, 2, 1)                             \
   F(NumberToFixed, 2, 1)                                   \
   F(NumberToExponential, 2, 1)                             \
   F(NumberToPrecision, 2, 1)                               \
   F(IsValidSmi, 1, 1)                                      \
                                                            \
   /* Classes support */                                    \
   F(ToMethod, 2, 1)                                        \
   F(HomeObjectSymbol, 0, 1)                                \
-  F(DefaultConstructorSuperCall, 0, 1)                     \
   F(DefineClass, 6, 1)                                     \
   F(DefineClassMethod, 3, 1)                               \
   F(ClassGetSourceCode, 1, 1)                              \
   F(LoadFromSuper, 3, 1)                                   \
   F(LoadKeyedFromSuper, 3, 1)                              \
   F(ThrowConstructorNonCallableError, 0, 1)                \
   F(ThrowNonMethodError, 0, 1)                             \
   F(ThrowUnsupportedSuperError, 0, 1)                      \
   F(HandleStepInForDerivedConstructors, 1, 1)              \
   F(StoreToSuper_Strict, 4, 1)                             \
@@ skipping 697 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_