Fix #1426 clearTimeout not correctly clearing a timeout

clearTimeout was not correctly handling the case of clearing a
timeout that is also scheduled to run at the same tick.

This fix adds a deletedKeys array that is checked whilst we are
running the scheduled functions for the current clock tick. If
a function exists in deletedKeys it will not be ran. deletedKeys
is then reset to an empty array.

spec/core/ClockSpec.js

@@ -680,7 +680,7 @@ describe("Clock (acceptance)", function() {
     expect(actualTimes).toEqual([baseTime.getTime(), baseTime.getTime() + 1, baseTime.getTime() + 3]);
   })
 
-  it('should be able to clear a timeout', function () {
+  it('correctly clears a scheduled timeout while the Clock is advancing', function () {
     var delayedFunctionScheduler = new jasmineUnderTest.DelayedFunctionScheduler(),
       global = {Date: Date, setTimeout: undefined},
       mockDate = new jasmineUnderTest.MockDate(global),
@@ -694,10 +694,26 @@ describe("Clock (acceptance)", function() {
       global.clearTimeout(timerId2);
     }, 100);
 
-    timerId2 = global.setTimeout(() => {
-      fail();
-    }, 100);
+    timerId2 = global.setTimeout(fail, 100);
 
     clock.tick(100);
   });
+
+  it('correctly clears a scheduled interval while the Clock is advancing', function () {
+    var delayedFunctionScheduler = new jasmineUnderTest.DelayedFunctionScheduler(),
+      global = {Date: Date, setTimeout: undefined},
+      mockDate = new jasmineUnderTest.MockDate(global),
+      clock = new jasmineUnderTest.Clock(global, function () { return delayedFunctionScheduler; }, mockDate);
+
+    clock.install();
+
+    var timerId2;
+    var timerId1 = global.setInterval(function () {
+      global.clearInterval(timerId2);
+    }, 100);
+
+    timerId2 = global.setInterval(fail, 100);
+
+    clock.tick(400);
+  });
 });