Make splitValueList work with functions e.g. calc

[lee-chase]

Currently, values are split by comma and then space. This is not sufficient to support functions like calc and rgb.

currently height: calc(1rem * 2); color: rgba(140, 140, 140, 0.5);

results in the following values being tested

• calc(1rem
• *
• 2)
• rgba(140
• 140
• 140
• 140
• 0.5)

These should be calc(1rem * 2) rgba(140, 140, 140, 0.5)