Searching by two words separated by at least two spaces causes the web browser to block

Steps to reproduce:

• perform a search for two words that are separated by at least 2 spaces (e.g.: "sandbox test")

Result:

• the browser blocks and a message box "warning: unresponsive script" is displayed

• XWiki version: I reproduced initially on 5.4.7. Tested also on 8.2.1 and this issue reproduces.
• Reproduced with web browsers: Chrome51/Firefox47IE11/