Fix more -Wsign-compare warnings in heap, mips, base, etc.

test/cctest/test-conversions.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 407 matching lines @@
   CheckNonArrayIndex(false, "42949672964294967296429496729694966");
 }
 
 TEST(NoHandlesForTryNumberToSize) {
   i::Isolate* isolate = CcTest::i_isolate();
   size_t result = 0;
   {
     SealHandleScope no_handles(isolate);
     Smi* smi = Smi::FromInt(1);
     CHECK(TryNumberToSize(smi, &result));
-    CHECK_EQ(result, 1);
+    CHECK_EQ(result, 1u);
   }
   result = 0;
   {
     HandleScope scope(isolate);
     Handle<HeapNumber> heap_number1 = isolate->factory()->NewHeapNumber(2.0);
     {
       SealHandleScope no_handles(isolate);
       CHECK(TryNumberToSize(*heap_number1, &result));
-      CHECK_EQ(result, 2);
+      CHECK_EQ(result, 2u);
     }
     Handle<HeapNumber> heap_number2 = isolate->factory()->NewHeapNumber(
         static_cast<double>(std::numeric_limits<size_t>::max()) + 10000.0);
     {
       SealHandleScope no_handles(isolate);
       CHECK(!TryNumberToSize(*heap_number2, &result));
     }
   }
 }