html/template: define the FuncMap type locally

This redefinition means that the public signature of html/template
does not refer to text/template.

Fixes #2546.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5487083

src/pkg/html/template/escape_test.go

@@ -654,7 +654,7 @@ func TestEscape(t *testing.T) {
 	for _, test := range tests {
 		tmpl := New(test.name)
 		// TODO: Move noescape into template/func.go
-		tmpl.Funcs(template.FuncMap{
+		tmpl.Funcs(FuncMap{
 			"noescape": func(a ...interface{}) string {
 				return fmt.Sprint(a...)
 			},
@@ -792,7 +792,7 @@ func TestEscapeSet(t *testing.T) {
 
 	// pred is a template function that returns the predecessor of a
 	// natural number for testing recursive templates.
-	fns := template.FuncMap{"pred": func(a ...interface{}) (interface{}, error) {
+	fns := FuncMap{"pred": func(a ...interface{}) (interface{}, error) {
 		if len(a) == 1 {
 			if i, _ := a[0].(int); i > 0 {
 				return i - 1, nil

src/pkg/html/template/template.go

@@ -154,12 +154,20 @@ func (t *Template) Name() string {
 	return t.text.Name()
 }
 
+// FuncMap is the type of the map defining the mapping from names to
+// functions. Each function must have either a single return value, or two
+// return values of which the second has type error. In that case, if the
+// second (error) argument evaluates to non-nil during execution, execution
+// terminates and Execute returns that error. FuncMap has the same base type
+// as template.FuncMap, copied here so clients need not import "text/template".
+type FuncMap map[string]interface{}
+
 // Funcs adds the elements of the argument map to the template's function map.
 // It panics if a value in the map is not a function with appropriate return
 // type. However, it is legal to overwrite elements of the map. The return
 // value is the template, so calls can be chained.
-func (t *Template) Funcs(funcMap template.FuncMap) *Template {
-	t.text.Funcs(funcMap)
+func (t *Template) Funcs(funcMap FuncMap) *Template {
+	t.text.Funcs(template.FuncMap(funcMap))
 	return t
 }