Remove obsolete DiffDOM workaround

Workaround is no longer necessary as of DiffDOM 4.2.1

See fiduswriter/diffDOM#90

Signed-off-by: Clark Fischer <clark.fischer@gmail.com>

src/utils/MessageDiffUtils.tsx

@@ -259,33 +259,6 @@ function renderDifferenceInDOM(originalRootNode: Node, diff: IDiff, diffMathPatc
     }
 }
 
-function routeIsEqual(r1: number[], r2: number[]): boolean {
-    return r1.length === r2.length && !r1.some((e, i) => e !== r2[i]);
-}
-
-// workaround for https://github.com/fiduswriter/diffDOM/issues/90
-function filterCancelingOutDiffs(originalDiffActions: IDiff[]): IDiff[] {
-    const diffActions = originalDiffActions.slice();
-
-    for (let i = 0; i < diffActions.length; ++i) {
-        const diff = diffActions[i]!;
-        if (diff.action === "removeTextElement") {
-            const nextDiff = diffActions[i + 1];
-            const cancelsOut =
-                nextDiff &&
-                nextDiff.action === "addTextElement" &&
-                nextDiff.text === diff.text &&
-                routeIsEqual(nextDiff.route, diff.route);
-
-            if (cancelsOut) {
-                diffActions.splice(i, 2);
-            }
-        }
-    }
-
-    return diffActions;
-}
-
 /**
  * Renders a message with the changes made in an edit shown visually.
  * @param {IContent} originalContent the content for the base message
@@ -300,9 +273,7 @@ export function editBodyDiffToHtml(originalContent: IContent, editContent: ICont
     // diffActions is an array of objects with at least a `action` and `route`
     // property. `action` tells us what the diff object changes, and `route` where.
     // `route` is a path on the DOM tree expressed as an array of indices.
-    const originaldiffActions = dd.diff(originalBody, editBody);
-    // work around https://github.com/fiduswriter/diffDOM/issues/90
-    const diffActions = filterCancelingOutDiffs(originaldiffActions);
+    const diffActions = dd.diff(originalBody, editBody);
     // for diffing text fragments
     const diffMathPatch = new DiffMatchPatch();
     // parse the base html message as a DOM tree, to which we'll apply the differences found.