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

Closes #1321

Author: michilu

pubspec.yaml

@@ -24,10 +24,10 @@ 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'
   mock: '>=0.10.0 <0.12.0'
   protractor: '0.0.5'
   unittest: '>=0.10.1 <0.12.0'
+  web_components: '>=0.3.3 <0.4.0'