Revert of WTF: Simplify RefPtr::operator bool.

third_party/WebKit/Source/wtf/RefPtr.h

Index: third_party/WebKit/Source/wtf/RefPtr.h
diff --git a/third_party/WebKit/Source/wtf/RefPtr.h b/third_party/WebKit/Source/wtf/RefPtr.h
index 1660f882f8b321cf8ee9605558c5af12319ffe17..eab641a66509aeca93b469c0f35c46e30c7ac44b 100644
--- a/third_party/WebKit/Source/wtf/RefPtr.h
+++ b/third_party/WebKit/Source/wtf/RefPtr.h
@@ -70,7 +70,10 @@
     ALWAYS_INLINE T* operator->() const { return m_ptr; }
 
     bool operator!() const { return !m_ptr; }
-    explicit operator bool() const { return m_ptr; }
+
+    // TODO(jbroman): Simplifying this in the obvious way causes a massive
+    // regression in a perf test on ARM. http://crbug.com/607208
+    explicit operator bool() const { return m_ptr ? &RefPtr::m_ptr : 0; }
 
     RefPtr& operator=(RefPtr o) { swap(o); return *this; }
     RefPtr& operator=(std::nullptr_t) { clear(); return *this; }