refactor(equals): Cleanup equals function for readability

- Removes unnecessary nested if condition
- Simplify check when one argument is a regex

Closes: #13650

Author: TehShrike

src/Angular.js

@@ -981,38 +981,37 @@ function equals(o1, o2) {
   if (o1 === null || o2 === null) return false;
   if (o1 !== o1 && o2 !== o2) return true; // NaN === NaN
   var t1 = typeof o1, t2 = typeof o2, length, key, keySet;
-  if (t1 == t2) {
-    if (t1 == 'object') {
-      if (isArray(o1)) {
-        if (!isArray(o2)) return false;
-        if ((length = o1.length) == o2.length) {
-          for (key = 0; key < length; key++) {
-            if (!equals(o1[key], o2[key])) return false;
-          }
-          return true;
-        }
-      } else if (isDate(o1)) {
-        if (!isDate(o2)) return false;
-        return equals(o1.getTime(), o2.getTime());
-      } else if (isRegExp(o1)) {
-        return isRegExp(o2) ? o1.toString() == o2.toString() : false;
-      } else {
-        if (isScope(o1) || isScope(o2) || isWindow(o1) || isWindow(o2) ||
-          isArray(o2) || isDate(o2) || isRegExp(o2)) return false;
-        keySet = createMap();
-        for (key in o1) {
-          if (key.charAt(0) === '$' || isFunction(o1[key])) continue;
+  if (t1 == t2 && t1 == 'object') {
+    if (isArray(o1)) {
+      if (!isArray(o2)) return false;
+      if ((length = o1.length) == o2.length) {
+        for (key = 0; key < length; key++) {
           if (!equals(o1[key], o2[key])) return false;
-          keySet[key] = true;
-        }
-        for (key in o2) {
-          if (!(key in keySet) &&
-              key.charAt(0) !== '$' &&
-              isDefined(o2[key]) &&
-              !isFunction(o2[key])) return false;
         }
         return true;
       }
+    } else if (isDate(o1)) {
+      if (!isDate(o2)) return false;
+      return equals(o1.getTime(), o2.getTime());
+    } else if (isRegExp(o1)) {
+      if (!isRegExp(o2)) return false;
+      return o1.toString() == o2.toString();
+    } else {
+      if (isScope(o1) || isScope(o2) || isWindow(o1) || isWindow(o2) ||
+        isArray(o2) || isDate(o2) || isRegExp(o2)) return false;
+      keySet = createMap();
+      for (key in o1) {
+        if (key.charAt(0) === '$' || isFunction(o1[key])) continue;
+        if (!equals(o1[key], o2[key])) return false;
+        keySet[key] = true;
+      }
+      for (key in o2) {
+        if (!(key in keySet) &&
+            key.charAt(0) !== '$' &&
+            isDefined(o2[key]) &&
+            !isFunction(o2[key])) return false;
+      }
+      return true;
     }
   }
   return false;