Completion: assign highest priority to dsl members in dsl context

Use the same style as for dsl for lookup items that belong to dsl

idea/idea-core/src/org/jetbrains/kotlin/idea/core/KotlinIndicesHelper.kt

@@ -141,7 +141,8 @@ class KotlinIndicesHelper(
     fun getCallableTopLevelExtensions(
             callTypeAndReceiver: CallTypeAndReceiver<*, *>,
             receiverTypes: Collection<KotlinType>,
-            nameFilter: (String) -> Boolean
+            nameFilter: (String) -> Boolean,
+            declarationFilter: (KtDeclaration) -> Boolean = { true }
     ): Collection<CallableDescriptor> {
         if (receiverTypes.isEmpty()) return emptyList()
 
@@ -157,7 +158,7 @@ class KotlinIndicesHelper(
                     KotlinTopLevelExtensionsByReceiverTypeIndex.receiverTypeNameFromKey(it) in receiverTypeNames
                     && nameFilter(KotlinTopLevelExtensionsByReceiverTypeIndex.callableNameFromKey(it))
                 }
-                .flatMap { index.get(it, project, scope).asSequence() }
+                .flatMap { index.get(it, project, scope).asSequence() }.filter(declarationFilter)
 
         val suitableExtensions = findSuitableExtensions(declarations, receiverTypes, callTypeAndReceiver.callType)