Calling |helpers.sign| instead of |Math.sign| directly for IE and Safari compatibility.

diff --git a/src/core/core.helpers.js b/src/core/core.helpers.js
index b77035dcf68397a617ef68b8063976a9ae1890e4..36cd4d379092bb973a4f96331a4d0c06e4d11577 100644 (file)
--- a/src/core/core.helpers.js
+++ b/src/core/core.helpers.js
@@ -366,7 +366,7 @@ module.exports = function(Chart) {
                        }
                        if (!pointBefore || pointBefore.model.skip) pointCurrent.mK = pointCurrent.deltaK;
                        else if (!pointAfter || pointAfter.model.skip) pointCurrent.mK = pointBefore.deltaK;
-                       else if (Math.sign(pointBefore.deltaK) != Math.sign(pointCurrent.deltaK)) pointCurrent.mK = 0;
+                       else if (this.sign(pointBefore.deltaK) != this.sign(pointCurrent.deltaK)) pointCurrent.mK = 0;
                        else pointCurrent.mK = (pointBefore.deltaK + pointCurrent.deltaK) / 2;
                }