Fix up float highlighting in Vim.

This fixes a regression introduced in #10793.

Having a colorscheme which highlights Float the same as Number (I
believe most do), I hadn't noticed that having the special case of "5."
floats (which was one of the added features in #10793) last made it take
precedence, and so it was left to @thestinger to notice it.

The regression meant that in `5.0`, the `5.` was a `rustFloat` (linked
by default to `Float`) and the `0` was a `rustDecNumber` (linked by
default to `Number`), and for `5.0f32` the `5.` was a `rustFloat` and
the `0f32` was a second `rustFloat` (and thus appeared correctly, though
for the wrong reason).

src/etc/vim/syntax/rust.vim

@@ -3,7 +3,7 @@
 " Maintainer:   Patrick Walton <pcwalton@mozilla.com>
 " Maintainer:   Ben Blum <bblum@cs.cmu.edu>
 " Maintainer:   Chris Morgan <me@chrismorgan.info>
-" Last Change:  2013 Dec 04
+" Last Change:  2013 Dec 10
 
 if version < 600
   syntax clear
@@ -160,14 +160,15 @@ syn match     rustHexNumber   display "\<0x[a-fA-F0-9_]\+\%([iu]\%(8\|16\|32\|64
 syn match     rustOctNumber   display "\<0o[0-7_]\+\%([iu]\%(8\|16\|32\|64\)\=\)\="
 syn match     rustBinNumber   display "\<0b[01_]\+\%([iu]\%(8\|16\|32\|64\)\=\)\="
 
-" To mark it as a float, it must have at least one of the three things integral values don't have:
+" Special case for numbers of the form "1." which are float literals, unless followed by
+" an identifier, which makes them integer literals with a method call or field access.
+" (This must go first so the others take precedence.)
+syn match     rustFloat       display "\<[0-9][0-9_]*\.\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\@!"
+" To mark a number as a normal float, it must have at least one of the three things integral values don't have:
 " a decimal point and more numbers; an exponent; and a type suffix.
 syn match     rustFloat       display "\<[0-9][0-9_]*\%(\.[0-9][0-9_]*\)\%([eE][+-]\=[0-9_]\+\)\=\(f32\|f64\)\="
 syn match     rustFloat       display "\<[0-9][0-9_]*\%(\.[0-9][0-9_]*\)\=\%([eE][+-]\=[0-9_]\+\)\(f32\|f64\)\="
 syn match     rustFloat       display "\<[0-9][0-9_]*\%(\.[0-9][0-9_]*\)\=\%([eE][+-]\=[0-9_]\+\)\=\(f32\|f64\)"
-" Special case for numbers of the form "1." which are float literals, unless followed by
-" an identifier, which makes them integer literals with a method call or field access.
-syn match     rustFloat       display "\<[0-9][0-9_]*\.\%([^[:cntrl:][:space:][:punct:][:digit:]]\|_\)\@!"
 
 " For the benefit of delimitMate
 syn region rustLifetimeCandidate display start=/&'\%(\([^'\\]\|\\\(['nrt0\\\"]\|x\x\{2}\|u\x\{4}\|U\x\{8}\)\)'\)\@!/ end=/[[:cntrl:][:space:][:punct:]]\@=\|$/ contains=rustSigil,rustLifetime