[ Merge of http://go/wvgerrit/119230 ] This patch adds an annotation to the one place in the codebase where we intentionally fall through between switch statement cases, in order to appease stricter compilers. Bug: 182058081 Test: compile, WV unit/integration tests Change-Id: I004a6a6e61681fcf22c6bf25d9b0284b8b64e776