Remove unnecessary casts and general code clean-up

pkg/analyzer/lib/src/generated/incremental_resolver.dart

Index: pkg/analyzer/lib/src/generated/incremental_resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/incremental_resolver.dart b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
index 490b676b6b6c61e7acce6677eeacf5e95d133e62..d0620ca7d847c6516e299222e2973123be3ff5f1 100644
--- a/pkg/analyzer/lib/src/generated/incremental_resolver.dart
+++ b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
@@ -1686,9 +1686,9 @@ class PoorMansIncrementalResolver {
           setElementDocumentationComment(parentElement, parent);
         } else if (parentElement == null && parent is FieldDeclaration) {
           for (VariableDeclaration field in parent.fields.variables) {
-            if (field.element is ElementImpl) {
-              setElementDocumentationComment(
-                  field.element as ElementImpl, parent);
+            Element fieldElement = field.element;
+            if (fieldElement is ElementImpl) {
+              setElementDocumentationComment(fieldElement, parent);
             }
           }
         }
@@ -1866,7 +1866,7 @@ class PoorMansIncrementalResolver {
   static Token _getBeginTokenNotComment(AstNode node) {
     Token oldBeginToken = node.beginToken;
     if (oldBeginToken is CommentToken) {
-      oldBeginToken = (oldBeginToken as CommentToken).parent;
+      return oldBeginToken.parent;
     }
     return oldBeginToken;
   }