Add page.CanRunOnBrowser. Add WebGL check for tough_webgl_cases pages

tools/telemetry/telemetry/page/page.py

Index: tools/telemetry/telemetry/page/page.py
diff --git a/tools/telemetry/telemetry/page/page.py b/tools/telemetry/telemetry/page/page.py
index d5835228c9cd499b760621a342b4bf1a259df386..58ced5e7802619b5e51a32eb00dea9b32480aff6 100644
--- a/tools/telemetry/telemetry/page/page.py
+++ b/tools/telemetry/telemetry/page/page.py
@@ -41,6 +41,16 @@ class Page(object):
   def RunNavigateSteps(self, action_runner):
     action_runner.NavigateToPage(self)
 
+  def CanRunOnBrowser(self, browser_info):
+    """Override this to returns whether this page can be run on specific
+    browser.
+
+    Args:
+      browser_info: an instance of telemetry.core.browser_info.BrowserInfo
+    """
+    assert browser_info
+    return True
+
   @property
   def page_set(self):
     return self._page_set