[Glitch] Only scroll to the compose form if it's not horizontally in the viewport

Port c07cca4727041ea5a5721acbc603d4bfb45a15a6 to glitch-soc

app/javascript/flavours/glitch/features/compose/components/compose_form.js

@@ -197,9 +197,12 @@ class ComposeForm extends ImmutablePureComponent {
 
   handleFocus = () => {
     if (this.composeForm && !this.props.singleColumn) {
+      const { left, right } = this.composeForm.getBoundingClientRect();
+      if (left < 0 || right > (window.innerWidth || document.documentElement.clientWidth)) {
         this.composeForm.scrollIntoView();
       }
     }
+  }
 
   //  This statement does several things:
   //  - If we're beginning a reply, and,