Fix disabling of textarea on readOnly=nocursor

Closes codemirror#4760

Author: marijnh

src/edit/options.js

@@ -125,9 +125,6 @@ export function defineOptions(CodeMirror) {
     if (val == "nocursor") {
       onBlur(cm)
       cm.display.input.blur()
-      cm.display.disabled = true
-    } else {
-      cm.display.disabled = false
     }
     cm.display.input.readOnlyChanged(val)
   })

src/input/TextareaInput.js

@@ -354,6 +354,7 @@ export default class TextareaInput {
 
   readOnlyChanged(val) {
     if (!val) this.reset()
+    this.textarea.disabled = val == "nocursor"
   }
 
   setUneditable() {}