move traverseSubviews method to SVGNode

ios/Elements/RNSVGDefs.m

@@ -13,11 +13,10 @@
 
 - (void)renderTo:(CGContextRef)context
 {
-    for (RNSVGNode *node in self.subviews) {
-        if ([node isKindOfClass:[RNSVGNode class]]) {
-            [node saveDefinition];
-        }
-    }
+    [self traverseSubviews:^(RNSVGNode *node) {
+        [node saveDefinition];
+        return YES;
+    }];
 }
 
 - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event

ios/Elements/RNSVGGroup.m

@@ -99,16 +99,5 @@
     }];
 }
 
-- (void)traverseSubviews:(BOOL (^)(RNSVGNode *node))block
-{
-    for (RNSVGNode *node in self.subviews) {
-        if ([node isKindOfClass:[RNSVGNode class]]) {
-            if (!block(node)) {
-                break;
-            }
-        }
-    }
-}
-
 
 @end