Store alphaChar as lower case in MenuItem's implementations

We should be working with lowercase everywehre (since SHIFT is also a
modifier). Also, in findItemsWithShortcutForKey, we only compare the
character against the lower case version of key pressed (and not the
upper case version).

Bug: 35992521
Test: Manual
Change-Id: I01f24afc5f6c9ef55d477806a64a4a1ec262f28a
2 files changed