MIPS: Fix `This CL enables precise source positions for all V8 compilers`

Fix c3a6ca68

Fix compilation failure on MIPS and GCC cross compile that started to appear
after the CL c3a6ca68 landed. The compilation
error is due to:

.././src/objects-inl.h:4129:54: error: assuming signed overflow does not occur
when assuming that (X + c) < X is always false [-Werror=strict-overflow]
   DCHECK(index >= 0 && length >= 0 && index + length >= index &&

BUG=

Review-Url: https://codereview.chromium.org/2501963002
Cr-Commit-Position: refs/heads/master@{#41067}

src/objects-inl.h

@@ -4128,14 +4128,14 @@ void ByteArray::set(int index, byte value) {
 }
 
 void ByteArray::copy_in(int index, const byte* buffer, int length) {
-  DCHECK(index >= 0 && length >= 0 && index + length >= index &&
+  DCHECK(index >= 0 && length >= 0 && length <= kMaxInt - index &&
          index + length <= this->length());
   byte* dst_addr = FIELD_ADDR(this, kHeaderSize + index * kCharSize);
   memcpy(dst_addr, buffer, length);
 }
 
 void ByteArray::copy_out(int index, byte* buffer, int length) {
-  DCHECK(index >= 0 && length >= 0 && index + length >= index &&
+  DCHECK(index >= 0 && length >= 0 && length <= kMaxInt - index &&
          index + length <= this->length());
   const byte* src_addr = FIELD_ADDR(this, kHeaderSize + index * kCharSize);
   memcpy(buffer, src_addr, length);