Minor: Pull up original property

idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangePropertySignatureDialog.kt

@@ -141,22 +141,22 @@ public class JetChangePropertySignatureDialog(
     }
 
     override fun doAction() {
-        val descriptor = (methodDescriptor as? JetMutableMethodDescriptor)?.original ?: methodDescriptor
+        val originalDescriptor = methodDescriptor.original
 
         val receiver = if (receiverTypeCheckBox?.isSelected() ?: false) {
-            descriptor.receiver ?: JetParameterInfo(callableDescriptor = descriptor.baseDescriptor,
-                                                    name = "receiver",
-                                                    defaultValueForCall = getDefaultReceiverValue())
+            originalDescriptor.receiver ?: JetParameterInfo(callableDescriptor = originalDescriptor.baseDescriptor,
+                                                            name = "receiver",
+                                                            defaultValueForCall = getDefaultReceiverValue())
         } else null
         receiver?.currentTypeText = receiverTypeField.getText()
-        val changeInfo = JetChangeInfo(descriptor,
+        val changeInfo = JetChangeInfo(originalDescriptor,
                                        nameField.getText(),
                                        null,
                                        returnTypeField.getText(),
                                        visibilityCombo.getSelectedItem() as Visibility,
                                        emptyList(),
                                        receiver,
-                                       descriptor.getMethod())
+                                       originalDescriptor.getMethod())
 
         invokeRefactoring(JetChangeSignatureProcessor(myProject, changeInfo, commandName ?: getTitle()))
     }
@@ -167,7 +167,7 @@ public class JetChangePropertySignatureDialog(
                 commandName: String,
                 descriptor: JetMethodDescriptor
         ): BaseRefactoringProcessor {
-            val originalDescriptor = (descriptor as? JetMutableMethodDescriptor)?.original ?: descriptor
+            val originalDescriptor = descriptor.original
             val changeInfo = JetChangeInfo(methodDescriptor = originalDescriptor, context = originalDescriptor.getMethod())
             changeInfo.setNewName(descriptor.getName())
             changeInfo.receiverParameterInfo = descriptor.receiver

idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignatureData.kt

@@ -92,6 +92,9 @@ public class JetChangeSignatureData(
         return JetParameterInfo(callableDescriptor = baseDescriptor, name = receiverName, type = receiverType)
     }
 
+    override val original: JetMethodDescriptor
+        get() = this
+
     override val primaryCallables: Collection<JetCallableDefinitionUsage<PsiElement>> by Delegates.lazy {
         descriptorsForSignatureChange.map {
             val declaration = DescriptorToSourceUtilsIde.getAnyDeclaration(baseDeclaration.getProject(), it)

idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignatureDialog.java

@@ -520,11 +520,8 @@ public class JetChangeSignatureDialog extends ChangeSignatureDialogBase<
         }
 
         String returnTypeText = returnTypeCodeFragment != null ? returnTypeCodeFragment.getText().trim() : "";
-        JetMethodDescriptor descriptor = methodDescriptor instanceof JetMutableMethodDescriptor
-                                         ? ((JetMutableMethodDescriptor) methodDescriptor).getOriginal()
-                                         : methodDescriptor;
         JetType returnType = getType((JetTypeCodeFragment) returnTypeCodeFragment);
-        return new JetChangeInfo(descriptor, methodName, returnType, returnTypeText,
+        return new JetChangeInfo(methodDescriptor.getOriginal(), methodName, returnType, returnTypeText,
                                  visibility, parameters, parametersModel.getReceiver(), defaultValueContext);
     }
 

idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetMethodDescriptor.kt

@@ -41,6 +41,8 @@ public trait JetMethodDescriptor : MethodDescriptor<JetParameterInfo, Visibility
         }
     }
 
+    val original: JetMethodDescriptor
+
     val baseDeclaration: PsiElement
     val baseDescriptor: CallableDescriptor
 

idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetMutableMethodDescriptor.kt

@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.idea.refactoring.changeSignature
 
 import org.jetbrains.kotlin.descriptors.Visibility
 
-public class JetMutableMethodDescriptor(val original: JetMethodDescriptor): JetMethodDescriptor by original {
+public class JetMutableMethodDescriptor(override val original: JetMethodDescriptor): JetMethodDescriptor by original {
     private val parameters: MutableList<JetParameterInfo> = original.getParameters()
 
     override var receiver: JetParameterInfo? = original.receiver