[Telemetry] Another fix for tough_pinch_zoom_cases after r282218.

IDs can't begin with a digit. However, this syntax allows it.

BUG=361809
TBR=dtu@chromium.org,chrishenry@google.com
NOTRY=True

Review URL: https://codereview.chromium.org/383263004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282721 0039d316-1c4b-4281-b951-d872f2087c98

tools/perf/page_sets/tough_pinch_zoom_cases.py

@@ -105,7 +105,7 @@ class GooglePlusPage(ToughPinchZoomCasesPage):
   def RunSmoothness(self, action_runner):
     interaction = action_runner.BeginGestureInteraction(
         'PinchAction', is_smooth=True)
-    action_runner.PinchElement(selector='#110031535020051778989-tab-bar')
+    action_runner.PinchElement(selector='[id="110031535020051778989-tab-bar"]')
     interaction.End()