Merge pull request #8964 from samjoch/follow-up-bug-823414

Bug 823414 - B2G browser gradient value does not match the gradient found in Settings (followup) r=me(cherry picked from commit b5d43350c1f1c5c784f74177b1eead5549034d27)

Conflicts:
	apps/browser/style/images/drawer-header-background@2x.png