angular_components contains multiple public libraries named the same, breaking dartdoc assumptions

[jcollins-g]

@kwalrath

Doing some testing for #1524 and noticed that angular_components now throws asserts in checked mode because of multiple public libraries having the same name.

generating docs for library angular_2 from angular_2.dart...
 warning: no canonical library found for dart-html.Window, not linking, from dart-html.Window: (file:///usr/local/google/home/jcollins/dart/all_sdks/2.0.0-dev.4.0/lib/html/dart2js/html_dart2js.dart:36875:7)
 warning: no canonical library found for injector.Injector, not linking, from injector.Injector: (file:///usr/local/google/home/jcollins/.pub-cache/hosted/pub.dartlang.org/angular-4.0.0/lib/src/di/injector/injector.dart:29:16)
 warning: no canonical library found for dart-async.Future, not linking, from dart-async.Future: (file:///usr/local/google/home/jcollins/dart/all_sdks/2.0.0-dev.4.0/lib/async/future.dart:149:16)
generating docs for library angular_2 from angular_2.dart...
 warning: no canonical library found for ng_zone.NgZone, not linking
    from ng_zone.NgZone: (file:///usr/local/google/home/jcollins/.pub-cache/hosted/pub.dartlang.org/angular-4.0.0/lib/src/core/zone/ng_zone.dart:78:7)
    referred to by angular_2.Angular2ManagedZone: (file:///usr/local/google/home/jcollins/dart/angular2_components/lib/utils/angular/managed_zone/angular_2.dart:14:7)
Generation failed: 'package:dartdoc/src/html/html_generator_instance.dart': Failed assertion: line 310 pos 12: '!_writtenFiles.contains(fullName)': is not true.
dart:core                                                     _AssertionError._throwNew
package:dartdoc/src/html/html_generator_instance.dart 310:12  HtmlGeneratorInstance._build
package:dartdoc/src/html/html_generator_instance.dart 200:5   HtmlGeneratorInstance.generateLibrary
package:dartdoc/src/html/html_generator_instance.dart 100:7   HtmlGeneratorInstance._generateDocs
package:dartdoc/src/html/html_generator_instance.dart 48:7    HtmlGeneratorInstance.generate
package:dartdoc/src/html/html_generator.dart 74:22            HtmlGenerator.generate
package:dartdoc/dartdoc.dart 187:23                           DartDoc.generateDocs
../dartdoc/bin/dartdoc.dart 208:44                            main.<fn>
package:stack_trace                                           Chain.capture
../dartdoc/bin/dartdoc.dart 207:9                             main
===== asynchronous gap ===========================
dart:async                                                    _Completer.completeError
package:dartdoc/src/html/html_generator_instance.dart 57:3    HtmlGeneratorInstance.generate
===== asynchronous gap ===========================
dart:async                                                    new Future.microtask
package:dartdoc/src/html/html_generator_instance.dart 44:27   HtmlGeneratorInstance.generate
package:dartdoc/src/html/html_generator.dart 74:22            HtmlGenerator.generate
package:dartdoc/dartdoc.dart 187:23                           DartDoc.generateDocs
===== asynchronous gap ===========================
dart:async                                                    new Future.microtask
package:dartdoc/dartdoc.dart 128:47                           DartDoc.generateDocs
../dartdoc/bin/dartdoc.dart 208:44                            main.<fn>
===== asynchronous gap ===========================
dart:async                                                    new Future.microtask
../dartdoc/bin/dartdoc.dart 207:26                            main.<fn>
package:stack_trace                                           Chain.capture
../dartdoc/bin/dartdoc.dart 207:9                             main


Process finished with exit code 255

Some examples of this:

• utils/browser/dom_service/angular_2.dart & utils/angular/managed_zone/angular_2.dart
• material_select/display_name.dart & model/ui/display_name.dart
• laminate/popup/module.dart & laminate/overlay/module.dart & theme/module.dart & laminate/ruler/module.dart & utils/browser/window/module.dart

The assert is not new, but while I was off on dart2now it had been a while since I had run angular2_components myself.

The consequence of this (assuming you're not in checked mode) is only one of the identically named libraries will show up in indexes and many links, with a lot of confusing internal linkage to and from elements in these libraries.

Proposed solution is to detect this situation and write libraries with name conflicts to different directories.

[jcollins-g]

Fixed in #1524.