Cleanup 1: split parts into their own libraries, remove unused imports

pkg/compiler/lib/src/js_backend/js_interop_analysis.dart

 // Copyright (c) 2015, 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.
 
 /// Analysis to determine how to generate code for typed JavaScript interop.
 library compiler.src.js_backend.js_interop_analysis;
 
-import '../common/names.dart' show Identifiers;
-import '../compiler.dart' show Compiler;
 import '../diagnostics/messages.dart' show MessageKind;
 import '../constants/values.dart'
     show
         ConstantValue,
         ConstructedConstantValue,
         ListConstantValue,
         NullConstantValue,
         StringConstantValue,
         TypeConstantValue;
 import '../elements/elements.dart'
@@ skipping 168 matching lines @@
           var name = backend.namer.invocationName(selector);
           statements.add(js.statement(
               'Function.prototype.# = function(#) { return this(#) }',
               [name, parameters, parameters]));
         }
       });
     });
     return new jsAst.Block(statements);
   }
 }