Rework go to symbol/class and getNavigationElement() for kotlin declarations

Based on work by geevee

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetDeclarationStub.java

@@ -17,6 +17,7 @@
 package org.jetbrains.jet.lang.psi;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.openapi.components.ServiceManager;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.stubs.IStubElementType;
 import com.intellij.psi.stubs.StubElement;
@@ -50,4 +51,17 @@ abstract class JetDeclarationStub<T extends StubElement> extends JetModifierList
         }
         return super.getParent();
     }
+
+    @NotNull
+    @Override
+    public PsiElement getNavigationElement() {
+        KotlinDeclarationNavigationPolicy navigationPolicy = ServiceManager.getService(KotlinDeclarationNavigationPolicy.class);
+        if (navigationPolicy != null) {
+            JetElement navigationElement = navigationPolicy.getNavigationElement(this);
+            if (navigationElement != null) {
+                return navigationElement;
+            }
+        }
+        return this;
+    }
 }

compiler/frontend/src/org/jetbrains/jet/lang/psi/KotlinDeclarationNavigationPolicy.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.lang.psi
+
+public trait KotlinDeclarationNavigationPolicy {
+    public fun getNavigationElement(declaration: JetDeclaration): JetElement?
+}