Replace boolean indications of strict mode by an enum value.

src/runtime.h

Index: src/runtime.h
diff --git a/src/runtime.h b/src/runtime.h
index 1d7c48ac214e8cae87d5ceaaadaf648eb51f1569..83c69e56cb943c5d9c4619717cb7cb0148744282 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -676,11 +676,9 @@ class Runtime : public AllStatic {
 //---------------------------------------------------------------------------
 // Constants used by interface to runtime functions.
 
-enum kDeclareGlobalsFlags {
-  kDeclareGlobalsEvalFlag = 1 << 0,
-  kDeclareGlobalsStrictModeFlag = 1 << 1,
-  kDeclareGlobalsNativeFlag = 1 << 2
-};
+class DeclareGlobalsEvalFlag:       public BitField<bool,           0, 1> {};
+class DeclareGlobalsStrictModeFlag: public BitField<StrictModeFlag, 1, 1> {};
+class DeclareGlobalsNativeFlag:     public BitField<bool,           2, 1> {};
 
 } }  // namespace v8::internal