diff --git a/vendor/google.golang.org/protobuf/internal/impl/pointer_reflect.go b/vendor/google.golang.org/protobuf/internal/impl/pointer_reflect.go
new file mode 100644
index 0000000..9e3ed82
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/internal/impl/pointer_reflect.go
@@ -0,0 +1,178 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build purego appengine
+
+package impl
+
+import (
+	"fmt"
+	"reflect"
+	"sync"
+)
+
+const UnsafeEnabled = false
+
+// Pointer is an opaque pointer type.
+type Pointer interface{}
+
+// offset represents the offset to a struct field, accessible from a pointer.
+// The offset is the field index into a struct.
+type offset struct {
+	index  int
+	export exporter
+}
+
+// offsetOf returns a field offset for the struct field.
+func offsetOf(f reflect.StructField, x exporter) offset {
+	if len(f.Index) != 1 {
+		panic("embedded structs are not supported")
+	}
+	if f.PkgPath == "" {
+		return offset{index: f.Index[0]} // field is already exported
+	}
+	if x == nil {
+		panic("exporter must be provided for unexported field")
+	}
+	return offset{index: f.Index[0], export: x}
+}
+
+// IsValid reports whether the offset is valid.
+func (f offset) IsValid() bool { return f.index >= 0 }
+
+// invalidOffset is an invalid field offset.
+var invalidOffset = offset{index: -1}
+
+// zeroOffset is a noop when calling pointer.Apply.
+var zeroOffset = offset{index: 0}
+
+// pointer is an abstract representation of a pointer to a struct or field.
+type pointer struct{ v reflect.Value }
+
+// pointerOf returns p as a pointer.
+func pointerOf(p Pointer) pointer {
+	return pointerOfIface(p)
+}
+
+// pointerOfValue returns v as a pointer.
+func pointerOfValue(v reflect.Value) pointer {
+	return pointer{v: v}
+}
+
+// pointerOfIface returns the pointer portion of an interface.
+func pointerOfIface(v interface{}) pointer {
+	return pointer{v: reflect.ValueOf(v)}
+}
+
+// IsNil reports whether the pointer is nil.
+func (p pointer) IsNil() bool {
+	return p.v.IsNil()
+}
+
+// Apply adds an offset to the pointer to derive a new pointer
+// to a specified field. The current pointer must be pointing at a struct.
+func (p pointer) Apply(f offset) pointer {
+	if f.export != nil {
+		if v := reflect.ValueOf(f.export(p.v.Interface(), f.index)); v.IsValid() {
+			return pointer{v: v}
+		}
+	}
+	return pointer{v: p.v.Elem().Field(f.index).Addr()}
+}
+
+// AsValueOf treats p as a pointer to an object of type t and returns the value.
+// It is equivalent to reflect.ValueOf(p.AsIfaceOf(t))
+func (p pointer) AsValueOf(t reflect.Type) reflect.Value {
+	if got := p.v.Type().Elem(); got != t {
+		panic(fmt.Sprintf("invalid type: got %v, want %v", got, t))
+	}
+	return p.v
+}
+
+// AsIfaceOf treats p as a pointer to an object of type t and returns the value.
+// It is equivalent to p.AsValueOf(t).Interface()
+func (p pointer) AsIfaceOf(t reflect.Type) interface{} {
+	return p.AsValueOf(t).Interface()
+}
+
+func (p pointer) Bool() *bool              { return p.v.Interface().(*bool) }
+func (p pointer) BoolPtr() **bool          { return p.v.Interface().(**bool) }
+func (p pointer) BoolSlice() *[]bool       { return p.v.Interface().(*[]bool) }
+func (p pointer) Int32() *int32            { return p.v.Interface().(*int32) }
+func (p pointer) Int32Ptr() **int32        { return p.v.Interface().(**int32) }
+func (p pointer) Int32Slice() *[]int32     { return p.v.Interface().(*[]int32) }
+func (p pointer) Int64() *int64            { return p.v.Interface().(*int64) }
+func (p pointer) Int64Ptr() **int64        { return p.v.Interface().(**int64) }
+func (p pointer) Int64Slice() *[]int64     { return p.v.Interface().(*[]int64) }
+func (p pointer) Uint32() *uint32          { return p.v.Interface().(*uint32) }
+func (p pointer) Uint32Ptr() **uint32      { return p.v.Interface().(**uint32) }
+func (p pointer) Uint32Slice() *[]uint32   { return p.v.Interface().(*[]uint32) }
+func (p pointer) Uint64() *uint64          { return p.v.Interface().(*uint64) }
+func (p pointer) Uint64Ptr() **uint64      { return p.v.Interface().(**uint64) }
+func (p pointer) Uint64Slice() *[]uint64   { return p.v.Interface().(*[]uint64) }
+func (p pointer) Float32() *float32        { return p.v.Interface().(*float32) }
+func (p pointer) Float32Ptr() **float32    { return p.v.Interface().(**float32) }
+func (p pointer) Float32Slice() *[]float32 { return p.v.Interface().(*[]float32) }
+func (p pointer) Float64() *float64        { return p.v.Interface().(*float64) }
+func (p pointer) Float64Ptr() **float64    { return p.v.Interface().(**float64) }
+func (p pointer) Float64Slice() *[]float64 { return p.v.Interface().(*[]float64) }
+func (p pointer) String() *string          { return p.v.Interface().(*string) }
+func (p pointer) StringPtr() **string      { return p.v.Interface().(**string) }
+func (p pointer) StringSlice() *[]string   { return p.v.Interface().(*[]string) }
+func (p pointer) Bytes() *[]byte           { return p.v.Interface().(*[]byte) }
+func (p pointer) BytesPtr() **[]byte       { return p.v.Interface().(**[]byte) }
+func (p pointer) BytesSlice() *[][]byte    { return p.v.Interface().(*[][]byte) }
+func (p pointer) WeakFields() *weakFields  { return (*weakFields)(p.v.Interface().(*WeakFields)) }
+func (p pointer) Extensions() *map[int32]ExtensionField {
+	return p.v.Interface().(*map[int32]ExtensionField)
+}
+
+func (p pointer) Elem() pointer {
+	return pointer{v: p.v.Elem()}
+}
+
+// PointerSlice copies []*T from p as a new []pointer.
+// This behavior differs from the implementation in pointer_unsafe.go.
+func (p pointer) PointerSlice() []pointer {
+	// TODO: reconsider this
+	if p.v.IsNil() {
+		return nil
+	}
+	n := p.v.Elem().Len()
+	s := make([]pointer, n)
+	for i := 0; i < n; i++ {
+		s[i] = pointer{v: p.v.Elem().Index(i)}
+	}
+	return s
+}
+
+// AppendPointerSlice appends v to p, which must be a []*T.
+func (p pointer) AppendPointerSlice(v pointer) {
+	sp := p.v.Elem()
+	sp.Set(reflect.Append(sp, v.v))
+}
+
+// SetPointer sets *p to v.
+func (p pointer) SetPointer(v pointer) {
+	p.v.Elem().Set(v.v)
+}
+
+func (Export) MessageStateOf(p Pointer) *messageState     { panic("not supported") }
+func (ms *messageState) pointer() pointer                 { panic("not supported") }
+func (ms *messageState) messageInfo() *MessageInfo        { panic("not supported") }
+func (ms *messageState) LoadMessageInfo() *MessageInfo    { panic("not supported") }
+func (ms *messageState) StoreMessageInfo(mi *MessageInfo) { panic("not supported") }
+
+type atomicNilMessage struct {
+	once sync.Once
+	m    messageReflectWrapper
+}
+
+func (m *atomicNilMessage) Init(mi *MessageInfo) *messageReflectWrapper {
+	m.once.Do(func() {
+		m.m.p = pointerOfIface(reflect.Zero(mi.GoReflectType).Interface())
+		m.m.mi = mi
+	})
+	return &m.m
+}