exp/template/html: add some tests for ">" attributes.

R=mikesamuel
CC=golang-dev
https://golang.org/cl/4956042

src/pkg/exp/template/html/escape_test.go

@@ -292,6 +292,18 @@ func TestEscapeText(t *testing.T) {
 			`<a href="'`,
 			context{state: stateURL, delim: delimDoubleQuote},
 		},
+		{
+			`<img alt="1">`,
+			context{state: stateText},
+		},
+		{
+			`<img alt="1>"`,
+			context{state: stateTag},
+		},
+		{
+			`<img alt="1>">`,
+			context{state: stateText},
+		},
 		{
 			`<input checked type="checkbox"`,
 			context{state: stateTag},