Wait for sweeper threads when expansion of old generation fails.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/351013002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22007 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/spaces.cc

@@ -2595,15 +2595,6 @@ HeapObject* PagedSpace::SlowAllocateRaw(int size_in_bytes) {
   // collection.
   if (!heap()->always_allocate() &&
       heap()->OldGenerationAllocationLimitReached()) {
-    return NULL;
-  }
-
-  // Try to expand the space and allocate in the new next page.
-  if (Expand()) {
-    ASSERT(CountTotalPages() > 1 || size_in_bytes <= free_list_.available());
-    return free_list_.Allocate(size_in_bytes);
-  }
-
     // If sweeper threads are active, wait for them at that point.
      if (collector->IsConcurrentSweepingInProgress()) {
        collector->WaitUntilSweepingCompleted();
@@ -2614,6 +2605,15 @@ HeapObject* PagedSpace::SlowAllocateRaw(int size_in_bytes) {
        if (object != NULL) return object;
      }
 
+    return NULL;
+  }
+
+  // Try to expand the space and allocate in the new next page.
+  if (Expand()) {
+    ASSERT(CountTotalPages() > 1 || size_in_bytes <= free_list_.available());
+    return free_list_.Allocate(size_in_bytes);
+  }
+
   // Finally, fail.
   return NULL;
 }