[Blink-WebWorkers] WorkerSharedTimer cancels extra delayed tasks.

LayoutTests/fast/workers/resources/worker-timeout-cancel-order.js

Index: LayoutTests/fast/workers/resources/worker-timeout-cancel-order.js
diff --git a/LayoutTests/fast/workers/resources/worker-timeout-cancel-order.js b/LayoutTests/fast/workers/resources/worker-timeout-cancel-order.js
new file mode 100644
index 0000000000000000000000000000000000000000..8334e71cdb0a7cf4b9736c9b45baa3b04ccc91a1
--- /dev/null
+++ b/LayoutTests/fast/workers/resources/worker-timeout-cancel-order.js
@@ -0,0 +1,8 @@
+self.postMessage("Test started.");
+// The test will create 3 timeouts with their intervals decreasing.
+// If the timeouts execute in order then the test is PASS.
+self.addEventListener('message', function(e) {
+    var t1 = setTimeout(function () { postMessage(1); }, 5);
+    setTimeout(function () { postMessage(2); postMessage("DONE"); }, 10);
+    clearTimeout(t1);
+}, false);