Start incremental marking on idle notification.

test/cctest/test-heap.cc

Index: test/cctest/test-heap.cc
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index 9e3eea4e7957dbfe66648014693ff9374cf84f68..b494336b002cf747e7f74f73110c15bce57a6d9e 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -1289,3 +1289,33 @@ TEST(CollectingAllAvailableGarbageShrinksNewSpace) {
   new_capacity = new_space->Capacity();
   CHECK(old_capacity == new_capacity);
 }
+
+
+TEST(IdleNotificationAdvancesIncrementalMarking) {
+  if (!FLAG_incremental_marking || !FLAG_incremental_marking_steps) return;
+  InitializeVM();
+  v8::HandleScope scope;
+  const char* source = "function binom(n, m) {"
+                       "  var C = [[1]];"
+                       "  for (var i = 1; i <= n; ++i) {"
+                       "    C[i] = [1];"
+                       "    for (var j = 1; j < i; ++j) {"
+                       "      C[i][j] = C[i-1][j-1] + C[i-1][j];"
+                       "    }"
+                       "    C[i][i] = 1;"
+                       "  }"
+                       "  return C[n][m];"
+                       "};"
+                       "binom(1000, 500)";
+  {
+    AlwaysAllocateScope aa_scope;
+    CompileRun(source);
+  }
+  if (HEAP->incremental_marking()->IsStopped()) {
+    HEAP->incremental_marking()->Start();
+  }
+  intptr_t old_size = HEAP->SizeOfObjects();
+  while (!HEAP->IdleNotification());
+  intptr_t new_size = HEAP->SizeOfObjects();
+  CHECK(new_size < old_size);
+}