message: view vega -> view vega source. Fixes
diff: @@ -80,7 +80,7 @@ const SVG_CIRCLES = `
  const I18N = {
  CLICK_TO_VIEW_ACTIONS: 'Click to view actions',
  - COMPILED_ACTION: 'View Vega',
  + COMPILED_ACTION: 'View Vega Source',
  EDITOR_ACTION: 'Open in Vega Editor',
  PNG_ACTION: 'Save as PNG',
  SOURCE_ACTION: 'View Source',
  