Pasting code to Code Macro hangs Chrome & FF browser

Steps to reproduce:

1. Access Confluence using Chrome/FF
2. Create a page & add Code Macro
3. Paste the following code into the Code Macro:

   <xsl:variable name="userMapping" select="mx:execute-formula('public.ECN.import.primetrade.match.users', concat('User:',normalize-space($userLabel)))"></xsl:variable>

4. Result: Nothing is pasted into the Code Macro but instead the browser just freezed/hanged

Workaround:

1. Use IE as an alternative browser to paste the code successfully into the Code Macro frame and the code will be rendered just fine and browser won't crashed.
2. Insert the code using wiki markup instead:

   <xsl:variable name="userMapping" select="mx:execute-formula('public.ECN.import.primetrade.match.users', concat('User:',normalize-space($userLabel)))"></xsl:variable>