MIPS: Fix big-endian after r21774/r21803.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 1db14733a6e2e8699879ec631e8b0ad6507c40b4..ab51b44b5397480ef319075293f7c076077fe03f 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -5517,7 +5517,8 @@ class Internals {
   // These values match non-compiler-dependent values defined within
   // the implementation of v8.
   static const int kHeapObjectMapOffset = 0;
-  static const int kMapInstanceTypeOffset = 1 * kApiPointerSize + kApiIntSize;
+  static const int kMapInstanceTypeAndBitFieldOffset =
+      1 * kApiPointerSize + kApiIntSize;
   static const int kStringResourceOffset = 3 * kApiPointerSize;
 
   static const int kOddballKindOffset = 3 * kApiPointerSize;
@@ -5595,7 +5596,9 @@ class Internals {
   V8_INLINE static int GetInstanceType(internal::Object* obj) {
     typedef internal::Object O;
     O* map = ReadField<O*>(obj, kHeapObjectMapOffset);
-    return ReadField<uint8_t>(map, kMapInstanceTypeOffset);
+    // Map::InstanceType is defined so that it will always be loaded into
+    // the LS 8 bits of one 16-bit word, regardless of endianess.
+    return ReadField<uint16_t>(map, kMapInstanceTypeAndBitFieldOffset) & 0xff;
   }
 
   V8_INLINE static int GetOddballKind(internal::Object* obj) {