The reverted code had two bugs in the tab switching logic:
1. closeNavigate() called switchTab() -> infinite recursion since
switchTab() calls closeNavigate() when leaving tabNavigate
2. currentTab was updated AFTER closeNavigate(), so the recursive
call hit the same condition over and over
Fix: move currentTab assignment before cleanup, use a wasNavigating
flag to track the old tab state, and make closeNavigate() only reset
nav UI (caller handles tab transition).
shawn
14687e7ba6