Add the named color `rebeccapurple` (#639)

Source/devtools/front_end/common/Color.js

 /*
  * Copyright (C) 2009 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 568 matching lines @@
     "palegreen":          [152,251,152],
     "paleturquoise":      [175,238,238],
     "palevioletred":      [219,112,147],
     "papayawhip":         [255,239,213],
     "peachpuff":          [255,218,185],
     "peru":               [205,133,63],
     "pink":               [255,192,203],
     "plum":               [221,160,221],
     "powderblue":         [176,224,230],
     "purple":             [128,0,128],
+    "rebeccapurple":      [102,51,153],
     "red":                [255,0,0],
     "rosybrown":          [188,143,143],
     "royalblue":          [65,105,225],
     "saddlebrown":        [139,69,19],
     "salmon":             [250,128,114],
     "sandybrown":         [244,164,96],
     "seagreen":           [46,139,87],
     "seashell":           [255,245,238],
     "sienna":             [160,82,45],
     "silver":             [192,192,192],
@@ skipping 36 matching lines @@
 WebInspector.Color.Format = {
     Original: "original",
     Nickname: "nickname",
     HEX: "hex",
     ShortHEX: "shorthex",
     RGB: "rgb",
     RGBA: "rgba",
     HSL: "hsl",
     HSLA: "hsla"
 }