MIPS: Add big-endian support for MIPS.

src/conversions-inl.h

Index: src/conversions-inl.h
diff --git a/src/conversions-inl.h b/src/conversions-inl.h
index e503eb5027a0456795fd6cacdec32782e8595326..af9576af313285bc5d9a423dbbed1b6fa140c146 100644
--- a/src/conversions-inl.h
+++ b/src/conversions-inl.h
@@ -75,7 +75,11 @@ inline unsigned int FastD2UI(double x) {
   if (x < k2Pow52) {
     x += k2Pow52;
     uint32_t result;
+#ifndef V8_TARGET_BIG_ENDIAN
     Address mantissa_ptr = reinterpret_cast<Address>(&x);
+#else
+    Address mantissa_ptr = reinterpret_cast<Address>(&x) + kIntSize;
+#endif
     // Copy least significant 32 bits of mantissa.
     OS::MemCopy(&result, mantissa_ptr, sizeof(result));
     return negative ? ~result + 1 : result;