fix #1669 Everything until cursor position is selected in IE8

lib/ace/mouse/default_handlers.js

@@ -109,8 +109,9 @@ function DefaultHandlers(mouseHandler) {
         pos = pos || this.editor.renderer.screenToTextCoordinates(this.x, this.y);
         var editor = this.editor;
         // allow double/triple click handlers to change selection
+        var shiftPresed = this.mousedownEvent.getShiftKey();
         setTimeout(function(){
-            if (this.mousedownEvent.getShiftKey()) {
+            if (shiftPresed) {
                 editor.selection.selectToPosition(pos);
             }
             else if (!this.$clickSelection) {