Turn off root scroller intervention on key_silk_cases page.

tools/perf/page_sets/key_silk_cases.py

Index: tools/perf/page_sets/key_silk_cases.py
diff --git a/tools/perf/page_sets/key_silk_cases.py b/tools/perf/page_sets/key_silk_cases.py
index f8fe4f9ff86f06c38bb2dbb7e3aca53ea9ab4fce..f6657eb36bcb11b0ac983268d83aab1daa71dabf 100644
--- a/tools/perf/page_sets/key_silk_cases.py
+++ b/tools/perf/page_sets/key_silk_cases.py
@@ -560,6 +560,13 @@ class Page26(KeySilkCasesPage):
     action_runner.Wait(1)
 
   def PerformPageInteractions(self, action_runner):
+    # Add a touch-action: none because this page prevent defaults all
+    # touch moves.
+    action_runner.ExecuteJavaScript('''
+        var style = document.createElement("style");
+        document.head.appendChild(style);
+        style.sheet.insertRule("body { touch-action: none }", 0);
+        ''')
     with action_runner.CreateGestureInteraction('ScrollAction'):
       action_runner.ScrollPage(distance=5000)