pass label through props

src/components/views/rooms/BasicMessageComposer.js

@@ -225,7 +225,7 @@ export default class BasicMessageEditor extends React.Component {
                 tabIndex="1"
                 onKeyDown={this._onKeyDown}
                 ref={ref => this._editorRef = ref}
-                aria-label={_t("Edit message")}
+                aria-label={this.props.label}
             ></div>
         </div>);
     }

src/components/views/rooms/EditMessageComposer.js

@@ -255,6 +255,7 @@ export default class EditMessageComposer extends React.Component {
                 model={this.model}
                 room={this._getRoom()}
                 initialCaret={this.props.editState.getCaret()}
+                label={_t("Edit message")}
             />
             <div className="mx_EditMessageComposer_buttons">
                 <AccessibleButton kind="secondary" onClick={this._cancelEdit}>{_t("Cancel")}</AccessibleButton>