Bug 1631681 - Turn on inputmode attribute on release channel of GeckoView. r=geckoview-reviewers,smaug,snorp

`inputmode` attribute is used by software keyboard, so let's tun on this on
GeckoView at first.

Differential Revision: https://phabricator.services.mozilla.com/D72596

modules/libpref/init/StaticPrefList.yaml

@@ -1919,10 +1919,14 @@
   value: true
   mirror: always
 
-# Is support for HTMLInputElement.inputMode enabled?
+# Is support for HTMLElement.inputMode enabled?
 - name: dom.forms.inputmode
   type: bool
+#if defined(ANDROID)
+  value: true
+#else
   value: @IS_NOT_RELEASE_OR_BETA@
+#endif
   mirror: always
 
 # Enable Directory API. By default, disabled.