Fix FSTTimerID strings in spec tests to match constants used in web. (#953)

Author: mikelehen

Firestore/Example/Tests/SpecTests/FSTSpecTests.mm

@@ -335,11 +335,11 @@ - (void)doRunTimer:(NSString *)timer {
     timerID = FSTTimerIDAll;
   } else if ([timer isEqualToString:@"listen_stream_idle"]) {
     timerID = FSTTimerIDListenStreamIdle;
-  } else if ([timer isEqualToString:@"listen_stream_connection"]) {
+  } else if ([timer isEqualToString:@"listen_stream_connection_backoff"]) {
     timerID = FSTTimerIDListenStreamConnectionBackoff;
   } else if ([timer isEqualToString:@"write_stream_idle"]) {
     timerID = FSTTimerIDWriteStreamIdle;
-  } else if ([timer isEqualToString:@"write_stream_connection"]) {
+  } else if ([timer isEqualToString:@"write_stream_connection_backoff"]) {
     timerID = FSTTimerIDWriteStreamConnectionBackoff;
   } else if ([timer isEqualToString:@"online_state_timeout"]) {
     timerID = FSTTimerIDOnlineStateTimeout;