go spec: line comments may end in EOF

Consistency argument: A valid Go program should
remain valid after stripping leading and trailing
whitespace. This was not true so far if the last
text in the source was a line comment.

R=iant, ken2, r, rsc, r2
CC=golang-dev
https://golang.org/cl/2906041

doc/go_spec.html

 <!-- title The Go Programming Language Specification -->
-<!-- subtitle Version of Oct 29, 2010 -->
+<!-- subtitle Version of Nov 4, 2010 -->
 
 <!--
 TODO
@@ -138,7 +138,7 @@ There are two forms of comments:
 <ol>
 <li>
 <i>Line comments</i> start with the character sequence <code>//</code>
-and continue through the next newline. A line comment acts like a newline.
+and stop at the end of the line. A line comment acts like a newline.
 </li>
 <li>
 <i>General comments</i> start with the character sequence <code>/*</code>