Update dependencies.

Author: bicknellr

bower.json

@@ -23,12 +23,12 @@
   "dependencies": {
     "iron-flex-layout": "PolymerElements/iron-flex-layout#2.0-preview",
     "font-roboto": "PolymerElements/font-roboto#^1.0.1",
-    "polymer": "polymer/polymer#2.0-preview"
+    "polymer": "Polymer/polymer#^2.0.0-rc.1"
   },
   "devDependencies": {
     "iron-demo-helpers": "PolymerElements/iron-demo-helpers#2.0-preview",
     "webcomponentsjs": "webcomponents/webcomponentsjs#^1.0.0-rc.1",
-    "web-component-tester": "v6.0.0-prerelease.5"
+    "web-component-tester": "^6.0.0-prerelease.6"
   },
   "variants": {
     "1.x": {
@@ -39,6 +39,7 @@
       },
       "devDependencies": {
         "iron-demo-helpers": "PolymerElements/iron-demo-helpers#^1.0.0",
+        "web-component-tester": "^4.0.0",
         "webcomponentsjs": "webcomponents/webcomponentsjs#^0.7.0"
       }
     }