1769 Update README to reflect the requirement to use fragment activity (cla: yes)

1772 Set device density to polylines (cla: yes)

1775 [in_app_purchase]fix the type casting issue (cla: yes)

1776 [all_plugins] Compile all plugins together (cla: yes)

1778 Enable version checker to be run on cirrus (cla: yes)

1779 Add a PR triage policy to the contributing guide. (cla: yes)

1780 [cloud_firestore] Transactions improvements (cla: yes)

1781 [cloud_firestore] Support for map fields in document pagination (cla: yes)

1782 [url_launcher]: add option to enable DOM storage in android webview (cla: yes)