add android synthetic element detecting helpers

compiler/frontend.android/src/org/jetbrains/jet/lang/resolve/android/AndroidUtil.kt

@@ -16,6 +16,10 @@
 
 package org.jetbrains.jet.lang.resolve.android
 
+import com.intellij.openapi.vfs.VirtualFile
+import com.intellij.psi.PsiFile
+import com.intellij.psi.PsiElement
+
 trait AndroidResource
 
 class AndroidID(val rawID: String): AndroidResource {
@@ -33,4 +37,20 @@ class AndroidID(val rawID: String): AndroidResource {
 
 class AndroidWidget(val id: String, val className: String): AndroidResource
 
-class AndroidManifest(val _package: String): AndroidResource
+class AndroidManifest(val _package: String): AndroidResource
+
+fun isAndroidSyntheticFile(f: VirtualFile?): Boolean {
+    if (f?.getName() == AndroidConst.SYNTHETIC_FILENAME) {
+        val userData = f?.getUserData(AndroidConst.ANDROID_SYNTHETIC);
+        return (userData != null && userData.equals("OK"))
+    }
+    return false
+}
+
+fun isAndroidSyntheticFile(f: PsiFile?): Boolean {
+    return isAndroidSyntheticFile(f?.getVirtualFile())
+}
+
+fun isAndroidSyntheticElement(element: PsiElement?): Boolean {
+    return isAndroidSyntheticFile(element?.getContainingFile())
+}