Fix removing marks generate useless operations (#2946)

packages/slate/src/commands/by-path.js

@@ -237,6 +237,10 @@ Commands.removeMarksByPath = (editor, path, offset, length, marks) => {
   const { document } = value
   const node = document.assertNode(path)
 
+  if (marks.intersect(node.marks).isEmpty()) {
+    return
+  }
+
   editor.withoutNormalizing(() => {
     // If it ends before the end of the node, we'll need to split to create a new
     // text with different marks.

packages/slate/test/history/undo/toggle-mark.js

@@ -0,0 +1,33 @@
+/** @jsx h */
+
+import h from '../../helpers/h'
+
+export default function(editor) {
+  editor.addMark('bold')
+  editor.flush().removeMark('bold')
+  editor.flush().undo()
+}
+
+export const input = (
+  <value>
+    <document>
+      <paragraph>
+        one <anchor />two<focus /> three
+      </paragraph>
+    </document>
+  </value>
+)
+
+export const output = (
+  <value>
+    <document>
+      <paragraph>
+        one{' '}
+        <b>
+          <anchor />two
+        </b>
+        <focus /> three
+      </paragraph>
+    </document>
+  </value>
+)