Fix potential NPE in L10nUtils.

It is possible that a call to the L10nUtils class will
come before it has been properly initialised (if the
user highlights a form very quickly onload for example) so move
the initialisation earlier in the WebView ctor so that it is
set up before the WebCore thread is started.

Change-Id: Iff5a1c16d04c47d001146184f753d2cc0cbbb404