Remove unnecessary casts and general code clean-up

pkg/analyzer/lib/src/dart/ast/ast.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.src.dart.ast.ast;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 754 matching lines @@
     ExecutableElement executableElement = null;
     if (propagatedElement != null) {
       executableElement = propagatedElement;
     } else {
       if (_leftHandSide is Identifier) {
         Identifier identifier = _leftHandSide as Identifier;
         Element leftElement = identifier.propagatedElement;
         if (leftElement is ExecutableElement) {
           executableElement = leftElement;
         }
-      }
-      if (_leftHandSide is PropertyAccess) {
+      } else if (_leftHandSide is PropertyAccess) {
         SimpleIdentifier identifier =
             (_leftHandSide as PropertyAccess).propertyName;
         Element leftElement = identifier.propagatedElement;
         if (leftElement is ExecutableElement) {
           executableElement = leftElement;
         }
       }
     }
     if (executableElement == null) {
       return null;
@@ skipping 14 matching lines @@
   ParameterElement get _staticParameterElementForRightHandSide {
     ExecutableElement executableElement = null;
     if (staticElement != null) {
       executableElement = staticElement;
     } else {
       if (_leftHandSide is Identifier) {
         Element leftElement = (_leftHandSide as Identifier).staticElement;
         if (leftElement is ExecutableElement) {
           executableElement = leftElement;
         }
-      }
-      if (_leftHandSide is PropertyAccess) {
+      } else if (_leftHandSide is PropertyAccess) {
         Element leftElement =
             (_leftHandSide as PropertyAccess).propertyName.staticElement;
         if (leftElement is ExecutableElement) {
           executableElement = leftElement;
         }
       }
     }
     if (executableElement == null) {
       return null;
     }
@@ skipping 8084 matching lines @@
   Iterable get childEntities => new ChildEntities()..add(token);
 
   @override
   Token get endToken => token;
 
   @override
   bool get isQualified {
     AstNode parent = this.parent;
     if (parent is PrefixedIdentifier) {
       return identical(parent.identifier, this);
-    }
-    if (parent is PropertyAccess) {
+    } else if (parent is PropertyAccess) {
       return identical(parent.propertyName, this);
-    }
-    if (parent is MethodInvocation) {
+    } else if (parent is MethodInvocation) {
       MethodInvocation invocation = parent;
       return identical(invocation.methodName, this) &&
           invocation.realTarget != null;
     }
     return false;
   }
 
   @override
   bool get isSynthetic => token.isSynthetic;
 
@@ skipping 1624 matching lines @@
       : super(null, null) {
     _name = _becomeParentOf(name);
     _initializer = _becomeParentOf(initializer);
   }
 
   @override
   Iterable get childEntities =>
       super._childEntities..add(_name)..add(equals)..add(_initializer);
 
   /**
-   * This overridden implementation of getDocumentationComment() looks in the
+   * This overridden implementation of [documentationComment] looks in the
    * grandparent node for Dartdoc comments if no documentation is specifically
    * available on the node.
    */
   @override
   Comment get documentationComment {
     Comment comment = super.documentationComment;
     if (comment == null) {
-      if (parent != null && parent.parent != null) {
-        AstNode node = parent.parent;
-        if (node is AnnotatedNode) {
-          return node.documentationComment;
-        }
+      AstNode node = parent?.parent;
+      if (node is AnnotatedNode) {
+        return node.documentationComment;
       }
     }
     return comment;
   }
 
   @override
   VariableElement get element =>
       _name != null ? (_name.staticElement as VariableElement) : null;
 
   @override
@@ skipping 394 matching lines @@
 
   @override
   dynamic/*=E*/ accept/*<E>*/(AstVisitor/*<E>*/ visitor) =>
       visitor.visitYieldStatement(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _expression?.accept(visitor);
   }
 }