Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/github.com/googleapis/gnostic/compiler/context.go

@@ -0,0 +1,43 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package compiler
+
+// Context contains state of the compiler as it traverses a document.
+type Context struct {
+	Parent            *Context
+	Name              string
+	ExtensionHandlers *[]ExtensionHandler
+}
+
+// NewContextWithExtensions returns a new object representing the compiler state
+func NewContextWithExtensions(name string, parent *Context, extensionHandlers *[]ExtensionHandler) *Context {
+	return &Context{Name: name, Parent: parent, ExtensionHandlers: extensionHandlers}
+}
+
+// NewContext returns a new object representing the compiler state
+func NewContext(name string, parent *Context) *Context {
+	if parent != nil {
+		return &Context{Name: name, Parent: parent, ExtensionHandlers: parent.ExtensionHandlers}
+	}
+	return &Context{Name: name, Parent: parent, ExtensionHandlers: nil}
+}
+
+// Description returns a text description of the compiler state
+func (context *Context) Description() string {
+	if context.Parent != nil {
+		return context.Parent.Description() + "." + context.Name
+	}
+	return context.Name
+}