Fix issue processwire/processwire-issues#418 to fix file/image drag-to-upload in IE11 using fix provided by @Toutouwai

wire/modules/Inputfield/InputfieldFile/InputfieldFile.js

@@ -423,7 +423,8 @@ $(document).ready(function() {
 				$(this).removeClass('ui-state-hover'); 
 				$(this).closest('.Inputfield').removeClass('pw-drag-in-file'); 
 			}, false);
-			dropArea.addEventListener("dragenter", function() { 
+			dropArea.addEventListener("dragenter", function(evt) {
+				evt.preventDefault();
 				$(this).addClass('ui-state-hover'); 
 				$(this).closest('.Inputfield').addClass('pw-drag-in-file');
 			}, false);

wire/modules/Inputfield/InputfieldImage/InputfieldImage.js

@@ -1203,7 +1203,8 @@ function InputfieldImage($) {
 					dragStop();
 				}, false);
 				
-				el.addEventListener("dragenter", function() {
+				el.addEventListener("dragenter", function(evt) {
+					evt.preventDefault();
 					dragStart();
 				}, false);