Disable drawing line for area charts

src/shape.line.js

@@ -206,7 +206,7 @@ c3_chart_internal_fn.lineWithRegions = function (d, x, y, _regions) {
 c3_chart_internal_fn.updateArea = function (durationForExit) {
     var $$ = this, d3 = $$.d3;
     $$.mainArea = $$.main.selectAll('.' + CLASS.areas).selectAll('.' + CLASS.area)
-        .data($$.lineData.bind($$));
+        .data($$.areaData.bind($$));
     $$.mainArea.enter().append('path')
         .attr("class", $$.classArea.bind($$))
         .style("fill", $$.color)

src/type.js

@@ -32,7 +32,7 @@ c3_chart_internal_fn.hasArcType = function (targets) {
 };
 c3_chart_internal_fn.isLineType = function (d) {
     var config = this.config, id = isString(d) ? d : d.id;
-    var is = !config.data_types[id] || ['line', 'spline', 'area', 'area-spline', 'step', 'area-step'].indexOf(config.data_types[id]) >= 0;
+    var is = !config.data_types[id] || ['line', 'spline', 'area-spline', 'step', 'area-step'].indexOf(config.data_types[id]) >= 0;
     return is;
 };
 c3_chart_internal_fn.isStepType = function (d) {
@@ -70,6 +70,9 @@ c3_chart_internal_fn.isDonutType = function (d) {
 c3_chart_internal_fn.isArcType = function (d) {
     return this.isPieType(d) || this.isDonutType(d) || this.isGaugeType(d);
 };
+c3_chart_internal_fn.areaData = function (d) {
+    return this.isAreaType(d) ? [d] : [];
+};
 c3_chart_internal_fn.lineData = function (d) {
     return this.isLineType(d) ? [d] : [];
 };