Fix gpu_unittests.isolate dependencies.

The gpu_unittests don't use any ANGLE or native graphics API
logic. Thus the isolate shouldn't include any dependency on things
it doesn't use or build. This should clear up runtime errors on the
bots involving gpu_unittests_run and libGLESv2.dll.

BUG=415981

Review URL: https://codereview.chromium.org/594203003

Cr-Commit-Position: refs/heads/master@{#296233}

chrome/gpu_unittests.isolate

@@ -3,7 +3,7 @@
 # found in the LICENSE file.
 {
   'includes': [
-    'angle.isolate',
+    '../base/base.isolate',
   ],
   'conditions': [
     ['OS=="android" or OS=="linux" or OS=="mac" or OS=="win"', {