cmd/compile: remove a stray word in the go:nosplit documentation

Change-Id: I7a85c0ad8aba2d50032c8faa58c83fb327f360cf
Reviewed-on: https://go-review.googlesource.com/16140Reviewed-by: Andrew Gerrand <adg@golang.org>

src/cmd/compile/doc.go

@@ -107,7 +107,7 @@ The //line directive is an historical special case; all other directives are of
 The //go:noescape directive specifies that the next declaration in the file, which
 must be a func without a body (meaning that it has an implementation not written
 in Go) does not allow any of the pointers passed as arguments to escape into the
-heap or into the values returned from the function. This information can be used as
+heap or into the values returned from the function. This information can be used
 during the compiler's escape analysis of Go code calling the function.
 
 	//go:nosplit