Bug 1627075 - Include WebGLParent.h in WebGLChild.h r=handyman,jgilbert

Depends on D77634

Differential Revision: https://phabricator.services.mozilla.com/D79536

dom/canvas/WebGLChild.h

@@ -11,6 +11,16 @@
 #include "mozilla/dom/PWebGLChild.h"
 #include "mozilla/dom/IpdlQueue.h"
 
+// This is a bit weird. Nothing directly in WebGLChild.h necessitates including
+// WebGLParent.h, but if we don't do this, we get compiler errors in the
+// generated code inside PWebGLChild.cpp. The error is due to a complex
+// dependency chain involving IpdlQueue, which I won't go into here. Including
+// WebGLParent.h inside WebGLChild.h is the simplest way we could think of to
+// avoid this issue. Including it in any of the code more directly involved in
+// the breaking dependency chain unfortunately introduces a cyclical dependency
+// between WebGLParent.h and PWebGLParent.h.
+#include "mozilla/dom/WebGLParent.h"
+
 namespace mozilla {
 
 class ClientWebGLContext;