fix colour settings of BeforeLabel and BeforeBody (#4783)

* fix colour settings of BeforeLabel and BeforeBody

* delete redundant variable declaration

* collect label colour setting.

src/core/core.tooltip.js

@@ -677,13 +677,16 @@ module.exports = function(Chart) {
 			};
 
 			// Before body lines
+			ctx.fillStyle = mergeOpacity(vm.bodyFontColor, opacity);
 			helpers.each(vm.beforeBody, fillLineOfText);
 
 			var drawColorBoxes = vm.displayColors;
 			xLinePadding = drawColorBoxes ? (bodyFontSize + 2) : 0;
 
 			// Draw body lines now
 			helpers.each(body, function(bodyItem, i) {
+				var textColor = mergeOpacity(vm.labelTextColors[i], opacity);
+				ctx.fillStyle = textColor;
 				helpers.each(bodyItem.before, fillLineOfText);
 
 				helpers.each(bodyItem.lines, function(line) {
@@ -701,7 +704,6 @@ module.exports = function(Chart) {
 						// Inner square
 						ctx.fillStyle = mergeOpacity(vm.labelColors[i].backgroundColor, opacity);
 						ctx.fillRect(pt.x + 1, pt.y + 1, bodyFontSize - 2, bodyFontSize - 2);
-						var textColor = mergeOpacity(vm.labelTextColors[i], opacity);
 						ctx.fillStyle = textColor;
 					}