Bug 1771344 - Add TextureClient::IsValid() check to PersistentBufferProviderShared::SetKnowsCompositor() r=gfx-reviewers,lsalzman

Device reset in test_device_reset.html replaces CompositorBridgeChild to a new one. And shutting down old CompositorBridgeChild also destroys TextureClients.

Differential Revision: https://phabricator.services.mozilla.com/D164175

gfx/layers/PersistentBufferProvider.cpp

@@ -257,7 +257,7 @@ bool PersistentBufferProviderShared::SetKnowsCompositor(
     // Get rid of everything else
     Destroy();
 
-    if (prevTexture) {
+    if (prevTexture && prevTexture->IsValid()) {
       RefPtr<TextureClient> newTexture =
           CreateTexture(aKnowsCompositor, mFormat, mSize, mWillReadFrequently);