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

test/unittests/zone/zone-chunk-list-unittest.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/zone/zone-chunk-list.h"
 
 #include "src/list-inl.h"
 #include "src/zone/accounting-allocator.h"
 #include "src/zone/zone.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 75 matching lines @@
 
   zone_chunk_list.Rewind(42);
 
   size_t count = 0;
 
   for (uintptr_t item : zone_chunk_list) {
     EXPECT_EQ(static_cast<size_t>(item), count);
     count++;
   }
 
-  EXPECT_EQ(count, 42);
+  EXPECT_EQ(count, 42u);
   EXPECT_EQ(count, zone_chunk_list.size());
 
   zone_chunk_list.Rewind(0);
 
   count = 0;
 
   for (uintptr_t item : zone_chunk_list) {
     USE(item);
     count++;
   }
 
-  EXPECT_EQ(count, 0);
+  EXPECT_EQ(count, 0u);
   EXPECT_EQ(count, zone_chunk_list.size());
 
   zone_chunk_list.Rewind(100);
 
   count = 0;
 
   for (uintptr_t item : zone_chunk_list) {
     EXPECT_EQ(static_cast<size_t>(item), count);
     count++;
   }
 
-  EXPECT_EQ(count, 0);
+  EXPECT_EQ(count, 0u);
   EXPECT_EQ(count, zone_chunk_list.size());
 }
 
 TEST(ZoneChunkList, FindTest) {
   AccountingAllocator allocator;
   Zone zone(&allocator, ZONE_NAME);
 
   ZoneChunkList<uintptr_t> zone_chunk_list(&zone);
 
   for (size_t i = 0; i < kItemCount; ++i) {
     zone_chunk_list.push_back(static_cast<uintptr_t>(i));
   }
 
   const size_t index = kItemCount / 2 + 42;
 
   EXPECT_EQ(*zone_chunk_list.Find(index), static_cast<uintptr_t>(index));
 
   *zone_chunk_list.Find(index) = 42;
 
-  EXPECT_EQ(*zone_chunk_list.Find(index), 42);
+  EXPECT_EQ(*zone_chunk_list.Find(index), 42u);
 }
 
 TEST(ZoneChunkList, CopyToTest) {
   AccountingAllocator allocator;
   Zone zone(&allocator, ZONE_NAME);
 
   ZoneChunkList<uintptr_t> zone_chunk_list(&zone);
 
   for (size_t i = 0; i < kItemCount; ++i) {
     zone_chunk_list.push_back(static_cast<uintptr_t>(i));
@@ skipping 47 matching lines @@
   zone_chunk_list.CopyTo(array);
 
   for (size_t i = 0; i < kItemCount; ++i) {
     EXPECT_EQ(array[i].a_, i);
     EXPECT_EQ(array[i].b_, i + 5);
   }
 }
 
 }  // namespace internal
 }  // namespace v8