lint: add Unwrap to common methods

Change-Id: Ia2f9aa6efeaff0d22a04af54340ccefdf0598f9a
GitHub-Last-Rev: 354a283
GitHub-Pull-Request: #487
Reviewed-on: https://go-review.googlesource.com/c/lint/+/221610
Run-TryBot: Rebecca Stambler <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Hyang-Ah Hana Kim <[email protected]>

Author: minizilla

lint.go

@@ -839,6 +839,7 @@ var commonMethods = map[string]bool{
 	"ServeHTTP": true,
 	"String":    true,
 	"Write":     true,
+	"Unwrap":    true,
 }
 
 // lintFuncDoc examines doc comments on functions and methods.

testdata/common-methods.go

@@ -14,3 +14,4 @@ func (T) String() string                                   { return "" }
 func (T) ServeHTTP(w http.ResponseWriter, r *http.Request) {}
 func (T) Read(p []byte) (n int, err error)                 { return 0, nil }
 func (T) Write(p []byte) (n int, err error)                { return 0, nil }
+func (T) Unwrap(err error) error                           { return nil }