Fix broken MultiFileHighlightingTest

Android resource folding builder should not run in non-Android projects

Author: 4u7

idea/idea-android/src/org/jetbrains/kotlin/android/folding/ResourceFoldingBuilder.kt

@@ -32,9 +32,9 @@ import com.intellij.openapi.editor.Document
 import com.intellij.openapi.module.ModuleUtilCore
 import com.intellij.openapi.util.text.StringUtil
 import com.intellij.psi.PsiClass
-import com.intellij.psi.PsiClassOwner
 import com.intellij.psi.PsiElement
 import com.intellij.psi.impl.source.SourceTreeToPsiMap
+import org.jetbrains.android.facet.AndroidFacet
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.uast.*
 import org.jetbrains.uast.visitor.AbstractUastVisitor
@@ -72,7 +72,7 @@ class ResourceFoldingBuilder : FoldingBuilderEx() {
     }
 
     override fun buildFoldRegions(root: PsiElement, document: Document, quick: Boolean): Array<FoldingDescriptor> {
-        if (root !is KtFile || quick && !UNIT_TEST_MODE || !isFoldingEnabled) {
+        if (root !is KtFile || quick && !UNIT_TEST_MODE || !isFoldingEnabled || AndroidFacet.getInstance(root) == null) {
             return emptyArray()
         }