Clean project code after #KT-3996 fix

No overload resolution ambiguity in smart-casts

idea/idea-analysis/src/org/jetbrains/kotlin/idea/refactoring/fqName/fqNameUtil.kt

@@ -33,8 +33,7 @@ public fun PsiElement.getKotlinFqName(): FqName? {
     return when (element) {
         is PsiPackage -> FqName(element.getQualifiedName())
         is PsiClass -> element.getQualifiedName()?.let { FqName(it) }
-        // as is necessary because of unresolved ambiguity: KT-3996
-        is PsiMember -> (element as PsiMember).getName()?.let { name ->
+        is PsiMember -> element.getName()?.let { name ->
             val prefix = element.getContainingClass()?.getQualifiedName()
             FqName(if (prefix != null) "$prefix.$name" else name)
         }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/structureView/KotlinInheritedMembersNodeProvider.kt

@@ -34,8 +34,7 @@ public class KotlinInheritedMembersNodeProvider: InheritedMembersNodeProvider<Tr
         val element = node.getElement()
         if (element !is KtClassOrObject) return listOf()
 
-        @Suppress("USELESS_CAST") // KT-3996 Workaround
-        val project = (element as NavigatablePsiElement).getProject()
+        val project = element.project
 
         val context = element.analyze()
         val descriptor = context[BindingContext.DECLARATION_TO_DESCRIPTOR, element]

idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinElementDescriptionProvider.kt

@@ -57,12 +57,8 @@ public class KotlinElementDescriptionProvider : ElementDescriptionProvider {
 
         if (targetElement !is PsiNamedElement || targetElement !is KtElement) return null
 
-        // as is necessary because of ambiguity: see KT-3996
-        val name = (targetElement as PsiNamedElement).getName()
-
         return when(location) {
-            is UsageViewLongNameLocation ->
-                name
+            is UsageViewLongNameLocation -> targetElement.getName()
             is RefactoringDescriptionLocation -> {
                 val kind = elementKind() ?: return null
                 val descriptor = targetDescriptor() ?: return null