Teach getOwnerFunction() in KtParamter work with stubs

compiler/frontend/src/org/jetbrains/kotlin/psi/KtParameter.java

@@ -173,10 +173,8 @@ public class KtParameter extends KtNamedDeclarationStub<KotlinParameterStub> imp
 
     @Nullable
     public KtFunction getOwnerFunction() {
-        PsiElement parent = getParent();
+        PsiElement parent = getParentByStub();
-        if (parent == null) return null;
+        if (!(parent instanceof KtParameterList)) return null;
-        PsiElement grandparent = parent.getParent();
+        return ((KtParameterList) parent).getOwnerFunction();
-        if (!(grandparent instanceof KtFunction)) return null;
-        return (KtFunction) grandparent;
     }
 }

compiler/frontend/src/org/jetbrains/kotlin/psi/KtParameterList.java

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.psi;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.psi.stubs.KotlinPlaceHolderStub;
@@ -61,4 +62,10 @@ public class KtParameterList extends KtElementImplStub<KotlinPlaceHolderStub<KtP
     public void removeParameter(@NotNull KtParameter parameter) {
         EditCommaSeparatedListHelper.INSTANCE.removeItem(parameter);
     }
+
+    public KtFunction getOwnerFunction() {
+        PsiElement parent = getParentByStub();
+        if (!(parent instanceof KtFunction)) return null;
+        return (KtFunction) parent;
+    }
 }