Revert "Make touchevent timestamp update on every non Stationary touch points"

This reverts commit 2131ec3a.

Reason for revert: Seems to have broken WebKit Linux Leak build.

https://ci.chromium.org/p/chromium/builders/ci/WebKit%20Linux%20Leak
https://ci.chromium.org/p/chromium/builders/ci/WebKit%20Linux%20Leak/2981

Original change's description:
> Make touchevent timestamp update on every non Stationary touch points
> 
> Touch event's timestamp is set from the |first_touch_pointer_event|'s
> timestamp. But in the case that this touch point is not changing but
> the others changed, this timestamp is not the latest pointerevent's
> timestamp.
> This CL changes it to use the the latest timestamp of the pointerevents
> in |touch_attribute_map|.
> 
> Bug: 973545
> Change-Id: I08be3f58e886f40eca17d515b36ec3a6424a38ef
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1705051
> Reviewed-by: David Bokan <bokan@chromium.org>
> Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
> Commit-Queue: Ella Ge <eirage@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#685612}

TBR=bokan@chromium.org,nzolghadr@chromium.org,eirage@chromium.org

Change-Id: Id5a4657d566006597c9b6db06e3736240899e8ef
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 973545
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1746789Reviewed-by: Scott Little <sclittle@chromium.org>
Commit-Queue: Scott Little <sclittle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685638}

third_party/blink/renderer/core/input/touch_event_manager.cc

@@ -244,10 +244,6 @@ WebCoalescedInputEvent TouchEventManager::GenerateWebCoalescedInputEvent() {
     event.touches[event.touches_length++] =
         CreateWebTouchPointFromWebPointerEvent(touch_pointer_event,
                                                touch_point_attribute->stale_);
-    if (!touch_point_attribute->stale_) {
-      event.SetTimeStamp(std::max(event.TimeStamp(),
-                                  touch_point_attribute->event_.TimeStamp()));
-    }
 
     // Only change the touch event type from move. So if we have two pointers
     // in up and down state we just set the touch event type to the first one

third_party/blink/web_tests/fast/events/touch/multi-touch-timestamp.html

-<script src="../../../resources/testharness.js"></script>
-<script src="../../../resources/testharnessreport.js"></script>
-<script src="../../../resources/testdriver.js"></script>
-<script src="../../../resources/testdriver-vendor.js"></script>
-<script src="../../../external/wpt/resources/testdriver-actions.js"></script>
-<div id="target" style="position:absolute; left:0px; right:0px; width:100%; height:100%; background:green">Target</div>
-<script>
-    var last_event = null;
-
-    function handleTouchEvents(e) {
-      if (last_event) {
-        t.step(function () {
-          assert_greater_than(e.timeStamp, last_event.timeStamp)
-        });
-      }
-      last_event = e;
-    }
-
-    function endTest(e) {
-      if (!e.touches.length) {
-        t.done();
-      }
-    }
-
-    let t = async_test("Test touch event timestamp with multiple finger.");
-
-    target.addEventListener("touchstart", handleTouchEvents);
-    target.addEventListener("touchmove", handleTouchEvents);
-    target.addEventListener("touchend", endTest);
-
-    new test_driver.Actions()
-            .addPointer("pointer1", "touch")
-            .addPointer("pointer2", "touch")
-            .pointerMove(0, 0, {origin: target, sourceName: "pointer1"})
-            .pointerDown({sourceName: "pointer1"})
-            .pointerMove(10, 10, {origin: target, sourceName: "pointer1"})
-            .pointerMove(10, 10, {origin: target, sourceName: "pointer2"})
-            .pointerDown({sourceName: "pointer2"})
-            .addTick()
-            .pointerMove(20, 20, {origin: target, sourceName: "pointer2"})
-            .addTick()
-            .pointerMove(30, 30, {origin: target, sourceName: "pointer1"})
-            .addTick()
-            .pointerMove(40, 40, {origin: target, sourceName: "pointer2"})
-            .addTick()
-            .pointerUp({sourceName: "pointer2"})
-            .pointerUp({sourceName: "pointer1"})
-            .send();
-</script>