Fix a couple of bugs referencing data values in template.

Adds tests and fixes for two cases that fail with the current release.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/217115

src/pkg/template/template.go

@@ -623,6 +623,9 @@ func (st *state) findVar(s string) reflect.Value {
 		if data == nil {
 			return nil
 		}
+		if intf, ok := data.(*reflect.InterfaceValue); ok {
+			data = intf.Elem()
+		}
 
 		switch typ := data.Type().(type) {
 		case *reflect.StructType:
@@ -706,6 +709,8 @@ func empty(v reflect.Value) bool {
 		return v.Get() == ""
 	case *reflect.StructValue:
 		return false
+	case *reflect.MapValue:
+		return false
 	case *reflect.ArrayValue:
 		return v.Len() == 0
 	case *reflect.SliceValue:

src/pkg/template/template_test.go

@@ -9,6 +9,7 @@ import (
 	"container/vector"
 	"fmt"
 	"io"
+	"json"
 	"testing"
 )
 
@@ -40,6 +41,7 @@ type S struct {
 	true          bool
 	false         bool
 	mp            map[string]string
+	json          interface{}
 	innermap      U
 	stringmap     map[string]string
 	bytes         []byte
@@ -340,6 +342,16 @@ var tests = []*Test{
 
 		out: "55\n",
 	},
+	&Test{
+		in: "{.section innermap}{.section mp}{innerkey}{.end}{.end}\n",
+
+		out: "55\n",
+	},
+	&Test{
+		in: "{.section json}{.repeated section maps}{a}{b}{.end}{.end}\n",
+
+		out: "1234\n",
+	},
 	&Test{
 		in: "{stringmap.stringkey1}\n",
 
@@ -391,6 +403,7 @@ func TestAll(t *testing.T) {
 	s.false = false
 	s.mp = make(map[string]string)
 	s.mp["mapkey"] = "Ahoy!"
+	s.json, _ = json.Decode("{\"maps\":[{\"a\":1,\"b\":2},{\"a\":3,\"b\":4}]}")
 	s.innermap.mp = make(map[string]int)
 	s.innermap.mp["innerkey"] = 55
 	s.stringmap = make(map[string]string)