Force scavenge in idle notification if we estimate that it will take long.

src/heap/gc-idle-time-handler-unittest.cc

Index: src/heap/gc-idle-time-handler-unittest.cc
diff --git a/src/heap/gc-idle-time-handler-unittest.cc b/src/heap/gc-idle-time-handler-unittest.cc
index b4f2f74f57b245b96f7e4f28908664ab3e012a50..8a3ac3c6a47980049196dcf171b911248503a269 100644
--- a/src/heap/gc-idle-time-handler-unittest.cc
+++ b/src/heap/gc-idle-time-handler-unittest.cc
@@ -112,7 +112,7 @@ TEST(GCIdleTimeHandler, EstimateMarkCompactTimeMax) {
 TEST(GCIdleTimeHandler, EstimateScavengeTimeInitial) {
   size_t size = 1 * MB;
   size_t time = GCIdleTimeHandler::EstimateScavengeTime(size, 0);
-  EXPECT_EQ(size / GCIdleTimeHandler::kInitialConservativeScavengeSpeed, time);
+  EXPECT_EQ(GCIdleTimeHandler::kLargeIdleTime, time);
 }