Fix hints

pkg/analysis_server/lib/src/computer/computer_outline.dart

Index: pkg/analysis_server/lib/src/computer/computer_outline.dart
diff --git a/pkg/analysis_server/lib/src/computer/computer_outline.dart b/pkg/analysis_server/lib/src/computer/computer_outline.dart
index c591b287b8d0eb1a92f74aca4125c3ec86f7781e..81e9b508d1394e7f520175f35c4c0617694fd25d 100644
--- a/pkg/analysis_server/lib/src/computer/computer_outline.dart
+++ b/pkg/analysis_server/lib/src/computer/computer_outline.dart
@@ -138,11 +138,10 @@ class DartUnitOutlineComputer {
     // unit or class member
     if (parent is CompilationUnit) {
       firstOffset = 0;
-      siblings = (parent as CompilationUnit).declarations;
+      siblings = parent.declarations;
     } else if (parent is ClassDeclaration) {
-      ClassDeclaration classDeclaration = parent as ClassDeclaration;
-      firstOffset = classDeclaration.leftBracket.end;
-      siblings = classDeclaration.members;
+      firstOffset = parent.leftBracket.end;
+      siblings = parent.members;
     } else {
       int offset = node.offset;
       return new _SourceRegion(offset, endOffset - offset);