Remove the obsolete Code::IsPregenerated flag.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index db92ecba8046504857e6eb8e27d99063bd24e38a..bbdefc14a5942122092dd2f82345b4b4d73a2bb6 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -5159,11 +5159,6 @@ class Code: public HeapObject {
   bool is_crankshafted();
   inline void set_is_crankshafted(bool value);
 
-  // For stubs, tells whether they should always exist, so that they can be
-  // called from other stubs.
-  inline bool is_pregenerated();
-  inline void set_is_pregenerated(bool value);
-
   // [optimizable]: For FUNCTION kind, tells if it is optimizable.
   inline bool optimizable();
   inline void set_optimizable(bool value);
@@ -5451,7 +5446,7 @@ class Code: public HeapObject {
   class TypeField: public BitField<StubType, 3, 1> {};
   class CacheHolderField: public BitField<InlineCacheHolderFlag, 5, 1> {};
   class KindField: public BitField<Kind, 6, 4> {};
-  class IsPregeneratedField: public BitField<bool, 10, 1> {};
+  // TODO(bmeurer): Bit 10 is available for free use. :-)
   class ExtraICStateField: public BitField<ExtraICState, 11, 6> {};
   class ExtendedExtraICStateField: public BitField<ExtraICState, 11,
       PlatformSmiTagging::kSmiValueSize - 11 + 1> {};  // NOLINT