Fixes url parsing bug -- reenables in-app auth flow

Summary:
Introduced a bug in URL parsing with the frictionless fix, which
failed to recognize urls that begin the parameter section with #

Test Plan:
Whitebox test using hackbook to force the in-app auth flow, and
confirm that the new line enables parsing of the returned URL

Reviewers: yariv, caabernathy, mmarucheck, vijaye

Reviewed By: mmarucheck

Differential Revision: https://phabricator.fb.com/D425267

src/FBDialog.m

@@ -566,7 +566,7 @@ - (NSString *) getStringFromUrl: (NSString*) url needle:(NSString *) needle {
         if (start.location != 0) {
             c = [url characterAtIndex:start.location - 1];
         }
-        if (c == '?' || c == '&') {        
+        if (c == '?' || c == '&' || c == '#') {        
             NSRange end = [[url substringFromIndex:start.location+start.length] rangeOfString:@"&"];
             NSUInteger offset = start.location+start.length;
             str = end.location == NSNotFound ?