highlight Kotlin files with errors in project view

#KT-8609 Fixed

idea/src/META-INF/plugin.xml

@@ -530,6 +530,8 @@
 
     <refactoring.pullUpHelperFactory language="jet" implementationClass="org.jetbrains.kotlin.idea.refactoring.pullUp.KotlinPullUpHelperFactory"/>
 
+    <problemFileHighlightFilter implementation="org.jetbrains.kotlin.idea.projectView.KotlinProblemFileHighlightFilter"/>
+
     <intentionAction>
       <className>org.jetbrains.kotlin.idea.intentions.IfNullToElvisIntention</className>
       <category>Kotlin</category>

idea/src/org/jetbrains/kotlin/idea/projectView/KotlinProblemFileHighlightFilter.kt

@@ -0,0 +1,26 @@
+
+/*
+ * Copyright 2010-2015 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 org.jetbrains.kotlin.idea.projectView
+
+import com.intellij.openapi.util.Condition
+import com.intellij.openapi.vfs.VirtualFile
+import org.jetbrains.kotlin.idea.JetFileType
+
+public class KotlinProblemFileHighlightFilter : Condition<VirtualFile> {
+    override fun value(t: VirtualFile): Boolean = t.fileType == JetFileType.INSTANCE
+}