Filter only .html files in web, keep those in lib/. This is as a temporary

pkg/polymer/lib/src/build/build_filter.dart

Index: pkg/polymer/lib/src/build/build_filter.dart
diff --git a/pkg/polymer/lib/src/build/build_filter.dart b/pkg/polymer/lib/src/build/build_filter.dart
index 61cdd076ae2bd19aa72ffccad23bad5a5d19fe8a..9bc8bd4fe0a7fbb14b4e506fd58b02255916cb55 100644
--- a/pkg/polymer/lib/src/build/build_filter.dart
+++ b/pkg/polymer/lib/src/build/build_filter.dart
@@ -24,6 +24,9 @@ class BuildFilter extends Transformer with PolymerTransformer {
   Future<bool> isPrimary(Asset input) => new Future.value(
       // nothing is filtered in debug mode
       options.releaseMode &&
+      // TODO(sigmund): remove this exclusion once we have dev_transformers
+      // (dartbug.com/14187)
+      input.id.path.startsWith('web/') &&
       // may filter non-entry HTML files and internal artifacts
       (input.id.extension == '.html' || input.id.extension == '.scriptUrls') &&
       // keep any entry points