Revert "DFL-2502 Don't handle horizontal scrolling and improve Mac scrolling speed."

This reverts commit bd7d788.

Accidental push.

Author: rcopera

src/ecma-debugger/js-source-view.js

@@ -981,54 +981,9 @@ cls.JsSourceView = function(id, name, container_class)
     }
   };
 
-  var _last_delta = 0;
-  var _accumulated_delta = 0;
-  const UNIT_LINES = 1;
-  const UNIT_PIXELS = 2;
-
-  this._get_lines_from_delta = function(delta, unit)
-  {
-    var lines;
-    if (unit == UNIT_LINES)
-      lines = delta;
-    else if (unit == UNIT_PIXELS)
-    {
-      if (_last_delta * delta < 0)
-        // Scroll direction has changed - reset accumulated delta.
-        _accumulated_delta = 0;
-
-      _last_delta = delta;
-      _accumulated_delta += delta;
-      // Convert pixels to lines.
-      delta = _accumulated_delta / window.defaults["js-source-line-height"];
-
-      if (Math.abs(delta) >= 1)
-      {
-        // Enough delta to scroll at least one line, round delta to
-        // integer and store remainder for later.
-        lines = delta >= 1 ? Math.floor(delta) : Math.ceil(delta);
-        _accumulated_delta = delta % 1;
-      }
-      else
-        // Not enough delta accumulated to scroll.
-        lines = 0;
-    }
-    else
-      lines = 0;
-
-    return lines;
-  }
-
   eventHandlers.mousewheel['scroll-js-source-view'] = function(event, target)
   {
-    if (event.wheelDeltaX !== undefined && event.wheelDeltaX != 0)
-      // Horizontal scrolling is handled natively by the browser.
-      return;
-
-    var unit = navigator.platform == 'MacIntel' ? UNIT_PIXELS : UNIT_LINES;
-    var lines = this._get_lines_from_delta(-event.wheelDelta / 3, unit);
-    if (lines)
-      this._scroll_lines(lines, event, target, unit);
+    this._scroll_lines((event.detail > 0 ? 1 : -1) * 3 , event, target);
   }.bind(this);
 
   this._handlers['show-window-go-to-line'] = function(event, target)