Assume: xhr.open("POST", "?q"); xhr.send(payload);

User expects that data shown in NetworkPanel is the same as "payload".
When payload contains non-ASCII chars, this is not true.

That is because postData is decoded with Latin-1 codec.

BUG=136170

Review URL: https://chromiumcodereview.appspot.com/22413002

git-svn-id: svn://svn.chromium.org/blink/trunk@155937 bbb929c8-8fbe-4397-9dbb-9b2b20218538