Bug 939396 - Fix <input type=range> so that the focus code doesn't overwrite the correct pre-focus value onclick. r=smaug

--HG--
extra : rebase_source : 095f67af802d9b63e7eda93e33d580c8d0286b9c

content/html/content/src/HTMLInputElement.cpp

@@ -3236,6 +3236,14 @@ HTMLInputElement::StartRangeThumbDrag(WidgetGUIEvent* aEvent)
   nsIPresShell::SetCapturingContent(this, CAPTURE_IGNOREALLOWED |
                                           CAPTURE_RETARGETTOELEMENT);
   nsRangeFrame* rangeFrame = do_QueryFrame(GetPrimaryFrame());
+
+  // Before we change the value, record the current value so that we'll
+  // correctly send a 'change' event if appropriate. We need to do this here
+  // because the 'focus' event is handled after the 'mousedown' event that
+  // we're being called for (i.e. too late to update mFocusedValue, since we'll
+  // have changed it by then).
+  GetValueInternal(mFocusedValue);
+
   SetValueOfRangeForUserEvent(rangeFrame->GetValueAtEventPoint(aEvent));
 }
 
@@ -3383,7 +3391,8 @@ HTMLInputElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
   if (aVisitor.mEvent->message == NS_FOCUS_CONTENT ||
       aVisitor.mEvent->message == NS_BLUR_CONTENT) {
     if (aVisitor.mEvent->message == NS_FOCUS_CONTENT &&
-        MayFireChangeOnBlur()) {
+        MayFireChangeOnBlur() &&
+        !mIsDraggingRange) { // StartRangeThumbDrag already set mFocusedValue
       GetValueInternal(mFocusedValue);
     }
 

content/html/content/test/forms/test_change_event.html

@@ -185,6 +185,10 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=722599
     is(rangeChange, 1, "Change event shouldn't be dispatched on range input element during drag of thumb");
     synthesizeMouse(range, centerOfRangeX, centerOfRangeY, { type: "mouseup" });
     is(rangeChange, 2, "Change event should be dispatched on range input element at end of drag");
+    range.blur();
+    is(rangeChange, 2, "Change event shouldn't be dispatched on range input element when range loses focus after a drag");
+    synthesizeMouse(range, centerOfRangeX - 10, centerOfRangeY, {});
+    is(rangeChange, 3, "Change event should be dispatched on range input element for a click that gives the range focus");
 
     //Input type change test.
     input = document.getElementById("input_checkbox");