Add null check for frame when creating WebCore::Performance.

Source/core/timing/Performance.cpp

Index: Source/core/timing/Performance.cpp
diff --git a/Source/core/timing/Performance.cpp b/Source/core/timing/Performance.cpp
index f3decc441656b93385a8321bf7d2773d642f2ba7..20dabe31993ff89da7ecc2d3b0630e9984578364 100644
--- a/Source/core/timing/Performance.cpp
+++ b/Source/core/timing/Performance.cpp
@@ -48,7 +48,7 @@ static const size_t defaultResourceTimingBufferSize = 150;
 Performance::Performance(LocalFrame* frame)
     : DOMWindowProperty(frame)
     , m_resourceTimingBufferSize(defaultResourceTimingBufferSize)
-    , m_referenceTime(frame->host() ? frame->document()->loader()->timing()->referenceMonotonicTime() : 0.0)
+    , m_referenceTime(frame && frame->host() ? frame->document()->loader()->timing()->referenceMonotonicTime() : 0.0)
     , m_userTiming(nullptr)
 {
     ScriptWrappable::init(this);