exp/html: when ignoring <textarea> tag, switch tokenizer out of raw text mode

Pass 1 additional test.

R=nigeltao
CC=golang-dev
https://golang.org/cl/6459060

src/pkg/exp/html/parse.go

@@ -1618,6 +1618,8 @@ func inSelectIM(p *parser) bool {
 				return false
 			}
 			// Ignore the token.
+			// In order to properly ignore <textarea>, we need to change the tokenizer mode.
+			p.tokenizer.rawTag = ""
 			return true
 		case a.Script:
 			return inHeadIM(p)

src/pkg/exp/html/testlogs/tests_innerHTML_1.dat.log

@@ -79,7 +79,7 @@ PASS "<table><td><td>"
 PASS "</select><option>"
 PASS "<input><option>"
 PASS "<keygen><option>"
-FAIL "<textarea><option>"
+PASS "<textarea><option>"
 FAIL "</html><!--abc-->"
 PASS "</frameset><frame>"
 PASS ""