replace useExpandedTraceDefaultColor with smarter DRYer logic

- now, Plots.clearExpandedTraceDefaultColors clears any trace
  attributes with valType: color and no set dflt.

Author: etpinard

src/components/colorscale/color_attributes.js

@@ -23,8 +23,7 @@ module.exports = function makeColorScaleAttributes(context) {
                 ' or an array of numbers that are mapped to the colorscale',
                 ' relative to the max and min values of the array or relative to',
                 ' `cmin` and `cmax` if set.'
-            ].join(''),
-            useExpandedTraceDefaultColor: true
+            ].join('')
         },
         colorscale: extendDeep({}, colorScaleAttributes.colorscale, {
             description: [

src/plots/plots.js

@@ -659,8 +659,8 @@ plots.linkSubplots = function(newFullData, newFullLayout, oldFullData, oldFullLa
     }
 };
 
-// This function clears any attributes with useExpandedTraceDefaultColor
-// set to true in the plot schema. This is needed because groupby (which
+// This function clears any trace attributes with valType: color and
+// no set dflt filed in the plot schema. This is needed because groupby (which
 // is the only transform for which this currently applies) supplies parent
 // trace defaults, then expanded trace defaults. The result is that `null`
 // colors are default-supplied and inherited as a color instead of a null.
@@ -675,7 +675,7 @@ plots.clearExpandedTraceDefaultColors = function(trace) {
     function locateColorAttrs(attr, attrName, attrs, level) {
         path[level] = attrName;
         path.length = level + 1;
-        if(attr.useExpandedTraceDefaultColor) {
+        if(attr.valType === 'color' && attr.dflt === undefined) {
             colorAttrs.push(path.join('.'));
         }
     }

src/traces/scatter/attributes.js

@@ -124,8 +124,7 @@ module.exports = {
         color: {
             valType: 'color',
             role: 'style',
-            description: 'Sets the line color.',
-            useExpandedTraceDefaultColor: true
+            description: 'Sets the line color.'
         },
         width: {
             valType: 'number',
@@ -204,7 +203,6 @@ module.exports = {
     fillcolor: {
         valType: 'color',
         role: 'style',
-        useExpandedTraceDefaultColor: true,
         description: [
             'Sets the fill color.',
             'Defaults to a half-transparent variant of the line color,',

test/jasmine/tests/plotschema_test.js

@@ -76,7 +76,7 @@ describe('plot schema', function() {
                     var valObject = valObjects[attr.valType],
                         opts = valObject.requiredOpts
                             .concat(valObject.otherOpts)
-                            .concat(['valType', 'description', 'role', 'editType', 'useExpandedTraceDefaultColor']);
+                            .concat(['valType', 'description', 'role', 'editType']);
 
                     Object.keys(attr).forEach(function(key) {
                         expect(opts.indexOf(key) !== -1).toBe(true, key, attr);