[ic] Remove unused ICStateField.

BUG=chromium:619016

Review-Url: https://codereview.chromium.org/2139373002
Cr-Commit-Position: refs/heads/master@{#37983}

src/objects-inl.h

@@ -5200,7 +5200,6 @@ Address Code::constant_pool() {
 
 Code::Flags Code::ComputeFlags(Kind kind, ExtraICState extra_ic_state,
                                CacheHolderFlag holder) {
-  // TODO(ishell): remove ICStateField.
   // Compute the bit mask.
   unsigned int bits = KindField::encode(kind) |
                       ExtraICStateField::encode(extra_ic_state) |

src/objects.h

@@ -5408,9 +5408,7 @@ class Code: public HeapObject {
   class ProfilerTicksField : public BitField<int, 4, 28> {};
 
   // Flags layout.  BitField<type, shift, size>.
-  class ICStateField : public BitField<InlineCacheState, 0, 2> {};
-  class HasUnwindingInfoField : public BitField<bool, ICStateField::kNext, 1> {
-  };
+  class HasUnwindingInfoField : public BitField<bool, 0, 1> {};
   class CacheHolderField
       : public BitField<CacheHolderFlag, HasUnwindingInfoField::kNext, 2> {};
   class KindField : public BitField<Kind, CacheHolderField::kNext, 5> {};