Fix s/Width/Height/ typo in draw.go. Fixes issue 531.
Fix s/Width/Height/ typo in draw.go.
Fixes issue 531.

R=r
CC=golang-dev
http://codereview.appspot.com/189078

apparentlymart/golang,tianon/debian-golang,h8liu/golang,h8liu/golang,dsriram/golang,ssrl/go,tianon/debian-golang,bdwalton/debian-golang,pombredanne/go-deleteme,dsriram/golang,ssrl/go,pombredanne/go-deleteme,bdwalton/debian-golang,gnanderson/go,ssrl/go,tianon/debian-golang,h8liu/golang,gnanderson/go,pombredanne/go-deleteme,apparentlymart/golang,nightlyone/golang,tianon/debian-golang,h8liu/golang,gnanderson/go,h8liu/golang,bdwalton/debian-golang,bdwalton/debian-golang,tv42/old-go,tianon/debian-golang,nightlyone/golang,pombredanne/go-deleteme,apparentlymart/golang,tianon/debian-golang,apparentlymart/golang,pombredanne/go-deleteme,bdwalton/debian-golang,tv42/old-go,nightlyone/golang,bdwalton/debian-golang,ssrl/go,ssrl/go,tv42/old-go,nightlyone/golang,bdwalton/debian-golang,nightlyone/golang,ssrl/go,apparentlymart/golang,dsriram/golang,tv42/old-go,gnanderson/go,tv42/old-go,ssrl/go,dsriram/golang,h8liu/golang,gnanderson/go,dsriram/golang,bdwalton/debian-golang,pombredanne/go-deleteme,apparentlymart/golang,h8liu/golang,tianon/debian-golang,dsriram/golang,pombredanne/go-deleteme,tv42/old-go,dsriram/golang,gnanderson/go,nightlyone/golang,apparentlymart/golang,tv42/old-go,tianon/debian-golang,gnanderson/go,nightlyone/golang