return installed constraints

Masonry/View+MASAdditions.m

@@ -15,7 +15,7 @@
     self.translatesAutoresizingMaskIntoConstraints = NO;
     MASConstraintMaker *constraintMaker = [[MASConstraintMaker alloc] initWithView:self];
     block(constraintMaker);
-    [constraintMaker install];
+    return [constraintMaker install];
 }
 
 #pragma mark - NSLayoutAttribute properties