Added static assert to BitField to ensure the contents fit within the field

Fixed ExtraICStateField which used 1 bits more than were available
BUG=

Review-Url: https://codereview.chromium.org/2258473002
Cr-Commit-Position: refs/heads/master@{#38697}

src/objects.h

@@ -5475,9 +5475,10 @@ class Code: public HeapObject {
       : public BitField<CacheHolderFlag, HasUnwindingInfoField::kNext, 2> {};
   class KindField : public BitField<Kind, CacheHolderField::kNext, 5> {};
   STATIC_ASSERT(NUMBER_OF_KINDS <= KindField::kMax);
-  class ExtraICStateField : public BitField<ExtraICState, KindField::kNext,
-                                            PlatformSmiTagging::kSmiValueSize -
-                                                KindField::kNext + 1> {};
+  class ExtraICStateField
+      : public BitField<ExtraICState, KindField::kNext,
+                        PlatformSmiTagging::kSmiValueSize - KindField::kNext> {
+  };
 
   // KindSpecificFlags1 layout (STUB, BUILTIN and OPTIMIZED_FUNCTION)
   static const int kStackSlotsFirstBit = 0;

src/utils.h

@@ -305,8 +305,9 @@ class BitFieldBase {
   static T decode(U value) {
     return static_cast<T>((value & kMask) >> shift);
   }
-};
 
+  STATIC_ASSERT((kNext - 1) / 8 < sizeof(U));
+};
 
 template <class T, int shift, int size>
 class BitField8 : public BitFieldBase<T, shift, size, uint8_t> {};