go/types: unresolved literal keys must be looked up in universe.

Fixes #4888.

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/7383051

src/pkg/go/types/expr.go

@@ -543,6 +543,8 @@ func (check *checker) compositeLitKey(key ast.Expr) {
 	if ident, ok := key.(*ast.Ident); ok && ident.Obj == nil {
 		if obj := check.pkg.Scope.Lookup(ident.Name); obj != nil {
 			check.register(ident, obj)
+		} else if obj := Universe.Lookup(ident.Name); obj != nil {
+			check.register(ident, obj)
 		} else {
 			check.errorf(ident.Pos(), "undeclared name: %s", ident.Name)
 		}

src/pkg/go/types/testdata/expr3.src

@@ -259,6 +259,8 @@ var index2 int = 2
 
 func map_literals() {
 	type M0 map[string]int
+	type M1 map[bool]int
+	type M2 map[*int]int
 
 	_ = M0{}
 	_ = M0{1 /* ERROR "missing key" */ }
@@ -267,11 +269,14 @@ func map_literals() {
 	_ = M0{"foo": 1, "bar": 2, "foo" /* ERROR "duplicate key" */ : 3 }
 
 	// map keys must be resolved correctly
-	// (for detials, see comment in go/parser/parser.go, method parseElement)
+	// (for details, see comment in go/parser/parser.go, method parseElement)
 	key1 := "foo"
 	_ = M0{key1: 1}
 	_ = M0{key2: 2}
 	_ = M0{key3 /* ERROR "undeclared name" */ : 2}
+
+	_ = M1{true: 1, false: 0}
+	_ = M2{nil: 0, &index2: 1}
 }
 
 var key2 string = "bar"
@@ -364,4 +369,4 @@ func _calls() {
 	fi(g2())
 	fi(0, g2)
 	fi(0, g2 /* ERROR "2-valued expression" */ ())
-}
\ No newline at end of file
+}