WindowAudioWorklet: gracefully handle detached use.

third_party/WebKit/Source/modules/webaudio/WindowAudioWorklet.cpp

Index: third_party/WebKit/Source/modules/webaudio/WindowAudioWorklet.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/WindowAudioWorklet.cpp b/third_party/WebKit/Source/modules/webaudio/WindowAudioWorklet.cpp
index 106c562eb847b48de321c2434447897f7327229e..2291e95d95599ce6505577f78030e99326bcf4fb 100644
--- a/third_party/WebKit/Source/modules/webaudio/WindowAudioWorklet.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/WindowAudioWorklet.cpp
@@ -29,6 +29,8 @@ WindowAudioWorklet& WindowAudioWorklet::from(LocalDOMWindow& window) {
 }
 
 Worklet* WindowAudioWorklet::audioWorklet(DOMWindow& window) {
+  if (!window.frame())
+    return nullptr;
   return from(toLocalDOMWindow(window)).audioWorklet(toLocalDOMWindow(window));
 }