Update perf expectations for xpdual/moz/vm_peak_b.
Update perf expectations for xpdual/moz/vm_peak_b.

This vm_peak_b increase is still under investigation.  Mark
it as expected while that work happens.

BUG=53619
TEST=xpdual/moz is green
TBR=nsylvain@chromium.org

Review URL: http://codereview.chromium.org/3286003

git-svn-id: http://src.chromium.org/svn/trunk/src@57830 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: cc1c8da710b0d43565508c03726b94b64c4ddc2d
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser