Make sure zeroLineIndex is defined (#6528)

diff --git a/src/core/core.scale.js b/src/core/core.scale.js
index 94fea1c93477a43ffa0f91f87de8f1168a37b427..74efdb4395a4774238fe560a253e151a78b5ec4c 100644 (file)
--- a/src/core/core.scale.js
+++ b/src/core/core.scale.js
@@ -202,6 +202,9 @@ function parseTickFontOptions(options) {
 }
 
 var Scale = Element.extend({
+
+       zeroLineIndex: 0,
+
        /**
         * Get the padding needed for the scale
         * @method getPadding