All strong mode cleaning of dart2js.

tests/compiler/dart2js/sourcemaps/output_structure.dart

 // Copyright (c) 2016, 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 sourcemap.output_structure;
 
 import 'dart:math' as Math;
-import 'html_parts.dart' show Annotation, CodeLine, JsonStrategy;
+import 'html_parts.dart' show CodeLine, JsonStrategy;
 
 // Constants used to identify the subsection of the JavaScript output. These
 // are specifically for the unminified full_emitter output.
 const String HEAD = '  var dart = [';
 const String TAIL = '  }], ';
 const String END = '  setupProgram(dart';
 
 final RegExp TOP_LEVEL_VALUE = new RegExp(r'^    (".+?"):');
 final RegExp TOP_LEVEL_FUNCTION =
     new RegExp(r'^    ([a-zA-Z0-9_$]+): \[?function');
@@ skipping 157 matching lines @@
         if (line.code.startsWith(END)) {
           return index;
         }
         index++;
       }
       return lines.length;
     }
 
     String readHeader(CodeLine line) {
       String code = line.code;
-      String ssaLineHeader;
       if (code.startsWith(HEAD)) {
         return code.substring(HEAD.length);
       } else if (code.startsWith(TAIL)) {
         return code.substring(TAIL.length);
       }
       return null;
     }
 
     List<LibraryBlock> computeHeaderMap(
         List<CodeLine> lines, int start, int end) {
@@ skipping 119 matching lines @@
           ..to = to
           ..codeSource = codeSource;
         json['children'].forEach(
             (child) => statics.children.add(fromJson(child, strategy)));
         return statics;
       case EntityKind.STATIC_FUNCTION:
         return new StaticFunction(name, from)
           ..to = to
           ..codeSource = codeSource;
     }
+    throw "Unhandled: $kind";
   }
 }
 
 /// A block defining the content of a Dart library.
 class LibraryBlock extends AbstractEntity {
   List<BasicEntity> children = <BasicEntity>[];
   int get headerEnd => from + 2;
   int get footerStart => to /* - 1*/;
 
   LibraryBlock(String name, int from) : super(name, from);
@@ skipping 373 matching lines @@
   }
 
   static CodeSource fromJson(Map json) {
     if (json == null) return null;
     CodeSource codeSource = new CodeSource(CodeKind.values[json['kind']],
         Uri.parse(json['uri']), json['name'], json['begin'], json['end']);
     json['members'].forEach((m) => codeSource.members.add(fromJson(m)));
     return codeSource;
   }
 }