Remove redundant autoprefixer call
Stringify prev source maps
Merge pull request #1525 from MohammadYounes/f1

Possible fix for error described in PR#1523
BrowserLink: Removed CSS sync

This will be in the box in VS2013 Update 4
Use maps toJSON behavior
Merge pull request #1526 from MohammadYounes/f2

postcss maps are using toJSON behavior