[dart-archive#1164] move web_components line to dev_dependencies in the pubspec.yaml

Closes dart-archive#1321

Author: michilu

pubspec.yaml

@@ -24,7 +24,6 @@ dependencies:
   intl: '>=0.8.7 <0.12.0'
   perf_api: '>=0.0.8 <0.1.0'
   route_hierarchical: '>=0.4.21 <0.5.0'
-  web_components: '>=0.3.3 <0.4.0'
 dev_dependencies:
   benchmark_harness: '>=1.0.0 <2.0.0'
   guinness: '>=0.1.9 <0.2.0'