KHABAROVSK, Russia — Watching the passing masses of protesters chanting “ Freedom!... Not for poverty or for the oligarchs sitting over there in the Kremlin.” The protests in Khabarovsk, a city 4, 000 miles east of Moscow, drew tens of thousands of people for a three-mile march through central streets for the third straight week on Saturday.... Putin won a tightly scripted referendum less than four weeks ago that rewrote the Constitution to allow him to stay in office until 2036....