eslint/tslint: correctly process language service timeout

- additionally check if the Future, returned by language service, was
cancelled (before was treated as no errors result).
Report to user as timeout error.
- tests for eslint/tslint highlighting + timeout
- test for tslint fix file

platform/util/src/com/intellij/util/ResultWithError.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2000-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.util;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * @author Irina.Chernushina on 6/20/2017.
+ */
+public class ResultWithError<Result, Error> {
+  @SuppressWarnings("unchecked") private static final ResultWithError EMPTY = new ResultWithError(null, null);
+  @Nullable private final Result myResult;
+  @Nullable private final Error myError;
+
+  private ResultWithError(@Nullable final Result result, @Nullable final Error error) {
+    myResult = result;
+    myError = error;
+  }
+
+  public static <R, E> ResultWithError<R, E> result(@NotNull R result) {
+    return new ResultWithError<R, E>(result, null);
+  }
+
+  public static <R, E> ResultWithError<R, E> error(@NotNull E error) {
+    return new ResultWithError<R, E>(null, error);
+  }
+
+  public static <R, E> ResultWithError<R, E> empty() {
+    //noinspection unchecked
+    return (ResultWithError<R, E>)EMPTY;
+  }
+
+  @Nullable
+  public Result getResult() {
+    return myResult;
+  }
+
+  @Nullable
+  public Error getError() {
+    return myError;
+  }
+}