Null check Owner() before calling SetNeedsStyleRecalc

Bug: 1158463
Change-Id: I6d9c29a72fae0e4cab62660883fa0b93d842b810
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2606381Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Commit-Queue: Evan Liu <evliu@google.com>
Cr-Commit-Position: refs/heads/master@{#839650}

third_party/blink/renderer/core/css/style_engine.cc

@@ -447,7 +447,7 @@ void StyleEngine::MediaQueryAffectingValueChanged(
       }
     }
 
-    if (style_needs_recalc) {
+    if (style_needs_recalc && text_track->Owner()) {
       // Use kSubtreeTreeStyleChange instead of RuleSet style invalidation
       // because it won't be expensive for tracks and we won't have dynamic
       // changes.