Fix build after r23316.

test/heap-unittests/heap-unittest.cc

Index: test/heap-unittests/heap-unittest.cc
diff --git a/test/heap-unittests/heap-unittest.cc b/test/heap-unittests/heap-unittest.cc
index aa7d21c04ec343e20fd827e48647fb17fed2136c..6e7b004ecaa3933aee1654af8fd6d09db8ef38f1 100644
--- a/test/heap-unittests/heap-unittest.cc
+++ b/test/heap-unittests/heap-unittest.cc
@@ -107,7 +107,8 @@ TEST_F(GCIdleTimeHandlerTest, IncrementalMarking1) {
   int idle_time_ms = 10;
   GCIdleTimeAction action = handler()->Compute(idle_time_ms, heap_state);
   EXPECT_EQ(DO_INCREMENTAL_MARKING, action.type);
-  EXPECT_GT(speed * idle_time_ms, action.parameter);
+  EXPECT_GT(speed * static_cast<size_t>(idle_time_ms),
+            static_cast<size_t>(action.parameter));
   EXPECT_LT(0, action.parameter);
 }
 
@@ -119,7 +120,8 @@ TEST_F(GCIdleTimeHandlerTest, IncrementalMarking2) {
   int idle_time_ms = 10;
   GCIdleTimeAction action = handler()->Compute(idle_time_ms, heap_state);
   EXPECT_EQ(DO_INCREMENTAL_MARKING, action.type);
-  EXPECT_GT(speed * idle_time_ms, action.parameter);
+  EXPECT_GT(speed * static_cast<size_t>(idle_time_ms),
+            static_cast<size_t>(action.parameter));
   EXPECT_LT(0, action.parameter);
 }