use Object.create over {}, fixes #12890

src/vs/editor/common/services/editorSimpleWorker.ts

@@ -124,7 +124,7 @@ export class MirrorModel extends MirrorModel2 implements ICommonModel {
 
 	public getAllUniqueWords(wordDefinition:RegExp, skipWordOnce?:string) : string[] {
 		var foundSkipWord = false;
-		var uniqueWords = {};
+		var uniqueWords = Object.create(null);
 		return this._getAllWords(wordDefinition).filter((word) => {
 			if (skipWordOnce && !foundSkipWord && skipWordOnce === word) {
 				foundSkipWord = true;

src/vs/editor/test/common/model/compatMirrorModel.test.ts

@@ -138,6 +138,13 @@ suite('Editor Model - MirrorModel', () => {
 		assert.equal(uniqueWords.length, 2);
 		assert.equal(uniqueWords[0], 'foo');
 		assert.equal(uniqueWords[1], 'bar');
+
+		model = new SimpleMirrorModel(null, [ 'toString', 'hasOwnProperty', 'foo' ], '\n', 1);
+		uniqueWords = model.getAllUniqueWords(DEFAULT_WORD_REGEXP);
+		assert.equal(uniqueWords.length, 3);
+		assert.equal(uniqueWords[0], 'toString');
+		assert.equal(uniqueWords[1], 'hasOwnProperty');
+		assert.equal(uniqueWords[2], 'foo');
 	});
 
 	test('word at/until pos', () => {