Fixed conflict dialog in IE8

- Fixed JS error that prevent the conflict dialog to open #5060
- Fixed JS error that prevented the overwrite case to run

apps/files/js/file-upload.js

@@ -124,7 +124,11 @@ OC.Upload = {
 	 */
 	onReplace:function(data){
 		this.log('replace', null, data);
-		data.data.append('resolution', 'replace');
+		if (data.data){
+			data.data.append('resolution', 'replace');
+		} else {
+			data.formData.push({name:'resolution',value:'replace'}); //hack for ie8
+		}
 		data.submit();
 	},
 	/**

core/js/oc-dialogs.js

@@ -234,7 +234,7 @@ var OCdialogs = {
 		var getCroppedPreview = function(file) {
 			var deferred = new $.Deferred();
 			// Only process image files.
-			var type = file.type.split('/').shift();
+			var type = file.type && file.type.split('/').shift();
 			if (window.FileReader && type === 'image') {
 				var reader = new FileReader();
 				reader.onload = function (e) {