Rename ZoomSpecField to FunctionSpecField

src/components/fields/FunctionSpecField.jsx

@@ -27,7 +27,7 @@ function isDataField(value) {
 /** Supports displaying spec field for zoom function objects
  * https://www.mapbox.com/mapbox-gl-style-spec/#types-function-zoom-property
  */
-export default class ZoomSpecProperty  extends React.Component {
+export default class FunctionSpecProperty  extends React.Component {
   static propTypes = {
       onChange: React.PropTypes.func.isRequired,
       fieldName: React.PropTypes.string.isRequired,

src/components/fields/PropertyGroup.jsx

@@ -1,6 +1,6 @@
 import React from 'react'
 
-import ZoomSpecField from './ZoomSpecField'
+import FunctionSpecField from './FunctionSpecField'
 const iconProperties = ['background-pattern', 'fill-pattern', 'line-pattern', 'fill-extrusion-pattern', 'icon-image']
 
 /** Extract field spec by {@fieldName} from the {@layerType} in the
@@ -54,7 +54,7 @@ export default class PropertyGroup extends React.Component {
       const layout = this.props.layer.layout || {}
       const fieldValue = fieldName in paint ? paint[fieldName] : layout[fieldName]
 
-      return <ZoomSpecField
+      return <FunctionSpecField
         onChange={this.onPropertyChange.bind(this)}
         key={fieldName}
         fieldName={fieldName}