builtin: add linkable-to declarations for iota and nil
Aids godoc.
R=golang-dev, gri, bradfitz
CC=golang-dev
https://golang.org/cl/7992044
diff --git a/src/pkg/builtin/builtin.go b/src/pkg/builtin/builtin.go
index 7b5e9ab..d3c1a5c 100644
--- a/src/pkg/builtin/builtin.go
+++ b/src/pkg/builtin/builtin.go
@@ -85,6 +85,15 @@
// used, by convention, to distinguish character values from integer values.
type rune rune
+// iota is a predeclared identifier representing the untyped integer ordinal
+// number of the current const specification in a (usually parenthesized)
+// const declaration. It is zero-indexed.
+const iota = 0 // Untyped int.
+
+// nil is a predeclared identifier representing the zero value for a
+// pointer, channel, func, interface, map, or slice type.
+var nil Type // Type must be a pointer, channel, func, interface, map, or slice type
+
// Type is here for the purposes of documentation only. It is a stand-in
// for any Go type, but represents the same type for any given function
// invocation.
