Fix legends not appearing on new cells

ui/src/shared/components/Dygraph.js

@@ -320,6 +320,7 @@ class Dygraph extends Component {
           </div>
         )}
         <div
+          onMouseEnter={this.handleShowLegend}
           ref={r => {
             this.graphRef = r
             this.props.dygraphRef(r)

ui/src/shared/components/DygraphLegend.js

@@ -43,7 +43,6 @@ class DygraphLegend extends Component {
   }
 
   highlightCallback = e => {
-    console.log('callback firing: ', this, e, e.target)
     this.setState({pageX: e.pageX})
     this.props.onShow(e)
   }

ui/src/shared/components/LineGraph.js

@@ -1,7 +1,6 @@
 import React, {Component} from 'react'
 import PropTypes from 'prop-types'
 import Dygraph from 'shared/components/Dygraph'
-import shallowCompare from 'react-addons-shallow-compare'
 
 import SingleStat from 'src/shared/components/SingleStat'
 import timeSeriesToDygraph from 'utils/timeSeriesTransformers'