New: CPEvent scrollingDeltaX, scrollingDeltaY and hasPreciseScrollingDeltas.

Refs #2013.

AppKit/CPEvent.j

@@ -68,6 +68,9 @@ var _CPEventPeriodicEventPeriod         = 0,
     float               _deltaX;
     float               _deltaY;
     float               _deltaZ;
+    float               _scrollingDeltaX;
+    float               _scrollingDeltaY;
+    BOOL                _hasPreciseScrollingDeltas;
 
 #if PLATFORM(DOM)
     BOOL                _suppressCappuccinoCut;
@@ -163,7 +166,9 @@ var _CPEventPeriodicEventPeriod         = 0,
 
         // Make sure these are 0 rather than nil.
         _deltaX = 0;
+        _scrollingDeltaX = 0;
         _deltaY = 0;
+        _scrollingDeltaY = 0;
         _deltaZ = 0;
     }
 
@@ -417,6 +422,31 @@ var _CPEventPeriodicEventPeriod         = 0,
     return _deltaZ;
 }
 
+- (BOOL)hasPreciseScrollingDeltas
+{
+    return !!_hasPreciseScrollingDeltas;
+}
+
+/*!
+    Returns the change in points on the x-axis for a mouse movement, unless hasPreciseScrollingDeltas is NO,
+    in which case the change is measured in number of "lines" or "rows" and needs to be multiplied as appropriate
+    to get change in pixels.
+*/
+- (float)scrollingDeltaX
+{
+    return _scrollingDeltaX;
+}
+
+/*!
+    Returns the change in points on the y-axis for a mouse movement, unless hasPreciseScrollingDeltas is NO,
+    in which case the change is measured in number of "lines" or "columns" and needs to be multiplied as appropriate
+    to get change in pixels.
+*/
+- (float)scrollingDeltaY
+{
+    return _scrollingDeltaY;
+}
+
 - (BOOL)_triggersKeyEquivalent:(CPString)aKeyEquivalent withModifierMask:aKeyEquivalentModifierMask
 {
     if (!aKeyEquivalent)

Tests/AppKit/CPEventTest.j

@@ -21,6 +21,8 @@
     [self assert:0 equals:[anEvent deltaX] message:"default event delta X should be 0"];
     [self assert:0 equals:[anEvent deltaY] message:"default event delta Y should be 0"];
     [self assert:0 equals:[anEvent deltaZ] message:"default event delta Z should be 0"];
+    [self assert:0 equals:[anEvent scrollingDeltaX] message:"default event scrolling delta X should be 0"];
+    [self assert:0 equals:[anEvent scrollingDeltaY] message:"default event scrolling delta Y should be 0"];
 }
 
 - (void)testDescription