Bug 1219980 - Ensure that long-press gestures don't get detected during test_basic_pan.html r=botond

Chaos mode can cause the the long-press timer to fire too early, so we have to
disable that. Also the pref to extend the timer is an int pref, not a char pref,
so drop the quotes (otherwise specialpowersAPI.js guesses the wrong type).

MozReview-Commit-ID: 4NefSNwwcht

--HG--
extra : rebase_source : b0d1328a7d2c363447360b207cef7754ebc9c9ba

gfx/layers/apz/test/mochitest/test_basic_pan.html

@@ -8,7 +8,6 @@
   <script type="application/javascript">
 
 SimpleTest.waitForExplicitFinish();
-SimpleTest.testInChaosMode();
 
 // this page just serially loads each one of the following test helper pages in
 // a new window and waits for it to call testDone()
@@ -53,8 +52,10 @@ window.onload = function() {
         ["apz.touch_start_tolerance", "0.0"],
         // The touchstart from the drag can turn into a long-tap if the touch-move
         // events get held up. Try to prevent that by making long-taps require
-        // a 10 second hold.
-        ["ui.click_hold_context_menus.delay", "10000"],
+        // a 10 second hold. Note that we also cannot enable chaos mode on this
+        // test for this reason, since chaos mode can cause the long-press timer
+        // to fire sooner than the pref dictates.
+        ["ui.click_hold_context_menus.delay", 10000],
         // The subtests in this test do touch-drags to pan the page, but we don't
         // want those pans to turn into fling animations, so we increase the
         // fling-stop threshold velocity to absurdly high.