test: fix build
syntax/*: update messages
sliceerr3.go: bizarre new error fixed by deleting a space.

I could have sworn I ran all.bash before submitting the CL that triggered these.

TBR=golang-dev@googlegroups.com

R=golang-dev
CC=golang-dev
https://golang.org/cl/12812044
diff --git a/test/slice3err.go b/test/slice3err.go
index c48ebfe..906b007 100644
--- a/test/slice3err.go
+++ b/test/slice3err.go
@@ -20,7 +20,7 @@
 	_ = array[::] // ERROR "middle index required in 3-index slice" "final index required in 3-index slice"
 	_ = array[i::] // ERROR "middle index required in 3-index slice" "final index required in 3-index slice"
 	_ = array[:j:] // ERROR "final index required in 3-index slice"
-	_ = array[i:j:] // ERROR  "final index required in 3-index slice"
+	_ = array[i:j:] // ERROR "final index required in 3-index slice"
 	_ = array[::k] // ERROR "middle index required in 3-index slice"
 	_ = array[i::k] // ERROR "middle index required in 3-index slice"
 	_ = array[:j:k]