Cherry-pick 270627@main (d0b51b0). https://bugs.webkit.org/show_bug.c…

…gi?id=264705

    [GStreamer][EME][Debug] Flaky assertions on weak pointer
    https://bugs.webkit.org/show_bug.cgi?id=264705

    Reviewed by Xabier Rodriguez-Calvar.

    Replace ASSERTs on WeakPtr by runtime checks, the pointer can be null, it's a valid scenario, so it
    shouldn't be in an ASSERT.

    * Source/WebCore/platform/encryptedmedia/CDMProxy.cpp:
    (WebCore::CDMInstanceProxy::startedWaitingForKey):
    (WebCore::CDMInstanceProxy::stoppedWaitingForKey):

    Canonical link: https://commits.webkit.org/270627@main

Source/WebCore/platform/encryptedmedia/CDMProxy.cpp

@@ -353,7 +353,8 @@ std::optional<KeyHandleValueVariant> CDMProxy::getOrWaitForKeyValue(const KeyIDT
 void CDMInstanceProxy::startedWaitingForKey()
 {
     ASSERT(!isMainThread());
-    ASSERT(m_player.get());
+    if (!m_player.get())
+        return;
 
     bool wasWaitingForKey = m_numDecryptorsWaitingForKey > 0;
     m_numDecryptorsWaitingForKey++;
@@ -368,7 +369,9 @@ void CDMInstanceProxy::startedWaitingForKey()
 void CDMInstanceProxy::stoppedWaitingForKey()
 {
     ASSERT(!isMainThread());
-    ASSERT(m_player.get());
+    if (!m_player.get())
+        return;
+
     ASSERT(m_numDecryptorsWaitingForKey > 0);
     m_numDecryptorsWaitingForKey--;
     bool isNobodyWaitingForKey = !m_numDecryptorsWaitingForKey;