Replace references to angle.isolate with gl.isolate.

This provides a single point where these dependencies can be updated.

BUG=509158
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1229213008

Cr-Commit-Position: refs/heads/master@{#338594}
diff --git a/extensions/extensions_browsertests.isolate b/extensions/extensions_browsertests.isolate
index 301e919..a060728 100644
--- a/extensions/extensions_browsertests.isolate
+++ b/extensions/extensions_browsertests.isolate
@@ -80,6 +80,6 @@
   'includes': [
     '../base/base.isolate',
     '../gin/v8.isolate',
-    '../third_party/angle/angle.isolate',
+    '../ui/gl/gl.isolate',
   ],
 }