Oilpan: Add a missing null check for Platform::current()

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index 6270835414dc436b35f708b6bdad82d70da4ed11..c0e907511d4fc75292ff4b0514ade04549bae142 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -663,8 +663,10 @@ void ThreadState::scheduleIdleGC()
         return;
     }
 
-    Platform::current()->currentThread()->scheduler()->postNonNestableIdleTask(FROM_HERE, WTF::bind<double>(&ThreadState::performIdleGC, this));
-    setGCState(IdleGCScheduled);
+    if (Platform::current()) {

[sof, 2015/04/23 18:22:41]

Platform::current() will exist, but it may not have a thread (cf.
initializeWithoutV8())

+        Platform::current()->currentThread()->scheduler()->postNonNestableIdleTask(FROM_HERE, WTF::bind<double>(&ThreadState::performIdleGC, this));
+        setGCState(IdleGCScheduled);
+    }
 }
 
 void ThreadState::scheduleIdleLazySweep()
@@ -675,7 +677,9 @@ void ThreadState::scheduleIdleLazySweep()
 
     // TODO(haraken): Remove this. Lazy sweeping is not yet enabled in non-oilpan builds.
 #if ENABLE(OILPAN)
-    Platform::current()->currentThread()->scheduler()->postIdleTask(FROM_HERE, WTF::bind<double>(&ThreadState::performIdleLazySweep, this));
+    if (Platform::current()) {
+        Platform::current()->currentThread()->scheduler()->postIdleTask(FROM_HERE, WTF::bind<double>(&ThreadState::performIdleLazySweep, this));
+    }
 #endif
 }