Fix suffix check (#2982)

* Fix suffix check

* Fix build failure due to let rather than const

---------

Co-authored-by: Jesus Sanchez <jesussa@microsoft.com>

Author: Frakcool

packages/roosterjs-content-model-dom/lib/modelApi/editing/retrieveModelFormatState.ts

@@ -276,10 +276,13 @@ function mergeValue<K extends keyof ContentModelFormatState>(
 }
 
 function px2Pt(px: string) {
-    if (px && px.indexOf('px') == px.length - 2) {
-        // Edge may not handle the floating computing well which causes the calculated value is a little less than actual value
-        // So add 0.05 to fix it
-        return Math.round(parseFloat(px) * 75 + 0.05) / 100 + 'pt';
+    if (px) {
+        const index = px.indexOf('px');
+        if (index !== -1 && index === px.length - 2) {
+            // Edge may not handle the floating computing well which causes the calculated value to be a little less than the actual value
+            // So add 0.05 to fix it
+            return Math.round(parseFloat(px) * 75 + 0.05) / 100 + 'pt';
+        }
     }
     return px;
-}
+}