Tests that Network.Response includes the charset
Network Enabled
Fetching with no charset
Network.Response.charset: 
Fetching with utf-8
Network.Response.charset: utf-8
Fetching with iso-8869-1
Network.Response.charset: iso-8859-1
Fetching utf-16 content
Network.Response.charset: utf-16
Response body: <p>Iñtërnâtiônàlizætiøn☃𝌆</p>