Revert "2012: fix mix-up of semantic/syntactic"

This reverts commit fbdfadebf1193ff057da2c1ca46db54437d0c9b1.

Reason for revert: The original is correct. It says both the old and new are syntactically good, so therefore it's semantics that change.

Change-Id: Iee019438eaa9afd7dac2862b36fae24b040d6ffb
Reviewed-on: https://go-review.googlesource.com/49730
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/2012/splash.article b/2012/splash.article
index fd2cda2..39b9104 100644
--- a/2012/splash.article
+++ b/2012/splash.article
@@ -1061,7 +1061,7 @@
 
 A key point about this transformation is that, because the input and
 output are both in the canonical format, the only changes made to
-the source code are syntactic ones.
+the source code are semantic ones.
 
 A similar but more intricate process allowed `gofmt` to be used to
 update the tree when the language no longer required semicolons