Fix CSS color order bug

[acupoftee]

This PR addresses #453

Before the first fix attempt made in PR #497, the array was only reversed in CodeModal.copyData(). The fix from 497 reversed the array in codeblock and copyData() with this technique: [...this.gradient.colors].reverse().join(','). This however created copies of the original array, and displayed code for the reversed gradient arrays.

To fix this, reverse() was removed from both codeblock, and copyData(). All copied arrays look like this:

[...this.gradient.colors].join(', ')

The gradient css will match the preview. Below is a demo featuring the gradient https://uigradients.com/#Margo referenced in the referenced issue:

Copied CSS w/ Fix:

background: #FFEFBA;  /* fallback for old browsers */
background: -webkit-linear-gradient(to top, #FFEFBA, #FFFFFF);  /* Chrome 10-25, Safari 5.1-6 */
background: linear-gradient(to top, #FFEFBA, #FFFFFF); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari7+ */

[acupoftee]

If accepted, would it also be helpful to include an additional test for the color order?