Auto merge of #157 - upsuper:source-location, r=SimonSapin
Auto merge of #157 - upsuper:source-location, r=SimonSapin

Use u32 for SourceLocation

I suppose nothing is going to be happy if a CSS file can contain over 4G lines or columns...

All Servo rules have `SourceLocation` stored, so reducing its size is probably worth.

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servo/rust-cssparser,servo/rust-cssparser