Added variables and made function private

Added variable for clientWidth and clientHeight;
Made function calculatePadding private

Author: andi-b

src/core/core.helpers.js

@@ -466,7 +466,10 @@ module.exports = function(Chart) {
 	helpers.getConstraintHeight = function(domNode) {
 		return getConstraintDimension(domNode, 'max-height', 'clientHeight');
 	};
-	helpers.calculatePadding = function(container, padding, parentDimension) {
+	/**
+	 * @private
+ 	 */
+	helpers._calculatePadding = function(container, padding, parentDimension) {
 		padding = helpers.getStyle(container, padding);
 
 		return padding.indexOf('%') > -1 ? parentDimension / parseInt(padding, 10) : parseInt(padding, 10);
@@ -477,10 +480,11 @@ module.exports = function(Chart) {
 			return domNode.clientWidth;
 		}
 
-		var paddingLeft = helpers.calculatePadding(container, 'padding-left', container.clientWidth);
-		var paddingRight = helpers.calculatePadding(container, 'padding-right', container.clientWidth);
+		var clientWidth = container.clientWidth;
+		var paddingLeft = helpers._calculatePadding(container, 'padding-left', clientWidth);
+		var paddingRight = helpers._calculatePadding(container, 'padding-right', clientWidth);
 
-		var w = container.clientWidth - paddingLeft - paddingRight;
+		var w = clientWidth - paddingLeft - paddingRight;
 		var cw = helpers.getConstraintWidth(domNode);
 		return isNaN(cw) ? w : Math.min(w, cw);
 	};
@@ -490,10 +494,11 @@ module.exports = function(Chart) {
 			return domNode.clientHeight;
 		}
 
-		var paddingTop = helpers.calculatePadding(container, 'padding-top', container.clientHeight);
-		var paddingBottom = helpers.calculatePadding(container, 'padding-bottom', container.clientHeight);
+		var clientHeight = container.clientHeight;
+		var paddingTop = helpers._calculatePadding(container, 'padding-top', clientHeight);
+		var paddingBottom = helpers._calculatePadding(container, 'padding-bottom', clientHeight);
 
-		var h = container.clientHeight - paddingTop - paddingBottom;
+		var h = clientHeight - paddingTop - paddingBottom;
 		var ch = helpers.getConstraintHeight(domNode);
 		return isNaN(ch) ? h : Math.min(h, ch);
 	};