chore(screenshot): local & CI integration (#15825)

core/scripts/screenshot/dev.js

@@ -0,0 +1,14 @@
+const IonicConnector = require('./ionic');
+
+class DevConnector extends IonicConnector {
+
+  async pullMasterBuild() {
+    await super.pullIonicMasterBuild();
+
+    const masterBuild = await super.getMasterBuild();
+    await this.generateJsonpDataUris(masterBuild);
+  }
+
+}
+
+module.exports = DevConnector;