Firestore: equality_matcher.ts: fix missing custom assertion failure message in deep equals (#7519)

* equality_matcher.ts: fix absence of custom message in assertion failure messages

* equality_matcher.ts: remove usage of the now-deleted `msg` argument

* equality_matcher.ts: fix type of `originalFunction`

Author: dconeybe

packages/firestore/test/util/equality_matcher.ts

@@ -123,7 +123,7 @@ function customDeepEqual(
 }
 
 /** The original equality function passed in by chai(). */
-let originalFunction: ((r: unknown, l: unknown) => boolean) | null = null;
+let originalFunction: ((expected: unknown) => void) | null = null;
 
 export function addEqualityMatcher(
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -136,15 +136,10 @@ export function addEqualityMatcher(
       const Assertion = chai.Assertion;
 
       // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-      const assertEql = (_super: (r: unknown, l: unknown) => boolean) => {
+      const assertEql = (_super: (expected: unknown) => void) => {
         originalFunction = originalFunction || _super;
-        return function (
-          this: Chai.Assertion,
-          expected?: unknown,
-          msg?: unknown
-        ): void {
+        return function (this: Chai.Assertion, expected?: unknown): void {
           if (isActive) {
-            utils.flag(this, 'message', msg);
             const actual = utils.flag(this, 'object');
 
             // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -161,7 +156,7 @@ export function addEqualityMatcher(
               /*showDiff=*/ true
             );
           } else if (originalFunction) {
-            originalFunction.call(this, expected, msg);
+            originalFunction.call(this, expected);
           }
         };
       };