Remove third_party/golang.org/x/mobile as it is no longer used with Go 1.5.

third_party/go/src/golang.org/x/mobile/f32/mat3.go

Index: third_party/go/src/golang.org/x/mobile/f32/mat3.go
diff --git a/third_party/go/src/golang.org/x/mobile/f32/mat3.go b/third_party/go/src/golang.org/x/mobile/f32/mat3.go
deleted file mode 100644
index 2577dbfa9263d481d81728010156c42e44c17cab..0000000000000000000000000000000000000000
--- a/third_party/go/src/golang.org/x/mobile/f32/mat3.go
+++ /dev/null
@@ -1,63 +0,0 @@
-// Copyright 2014 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.
-
-package f32
-
-import "fmt"
-
-// A Mat3 is a 3x3 matrix of float32 values.
-// Elements are indexed first by row then column, i.e. m[row][column].
-type Mat3 [3]Vec3
-
-func (m Mat3) String() string {
-	return fmt.Sprintf(`Mat3[% 0.3f, % 0.3f, % 0.3f,
-     % 0.3f, % 0.3f, % 0.3f,
-     % 0.3f, % 0.3f, % 0.3f]`,
-		m[0][0], m[0][1], m[0][2],
-		m[1][0], m[1][1], m[1][2],
-		m[2][0], m[2][1], m[2][2])
-}
-
-func (m *Mat3) Identity() {
-	*m = Mat3{
-		{1, 0, 0},
-		{0, 1, 0},
-		{0, 0, 1},
-	}
-}
-
-func (m *Mat3) Eq(n *Mat3, epsilon float32) bool {
-	for i := range m {
-		for j := range m[i] {
-			diff := m[i][j] - n[i][j]
-			if diff < -epsilon || +epsilon < diff {
-				return false
-			}
-		}
-	}
-	return true
-}
-
-// Mul stores a × b in m.
-func (m *Mat3) Mul(a, b *Mat3) {
-	// Store the result in local variables, in case m == a || m == b.
-	m00 := a[0][0]*b[0][0] + a[0][1]*b[1][0] + a[0][2]*b[2][0]
-	m01 := a[0][0]*b[0][1] + a[0][1]*b[1][1] + a[0][2]*b[2][1]
-	m02 := a[0][0]*b[0][2] + a[0][1]*b[1][2] + a[0][2]*b[2][2]
-	m10 := a[1][0]*b[0][0] + a[1][1]*b[1][0] + a[1][2]*b[2][0]
-	m11 := a[1][0]*b[0][1] + a[1][1]*b[1][1] + a[1][2]*b[2][1]
-	m12 := a[1][0]*b[0][2] + a[1][1]*b[1][2] + a[1][2]*b[2][2]
-	m20 := a[2][0]*b[0][0] + a[2][1]*b[1][0] + a[2][2]*b[2][0]
-	m21 := a[2][0]*b[0][1] + a[2][1]*b[1][1] + a[2][2]*b[2][1]
-	m22 := a[2][0]*b[0][2] + a[2][1]*b[1][2] + a[2][2]*b[2][2]
-	m[0][0] = m00
-	m[0][1] = m01
-	m[0][2] = m02
-	m[1][0] = m10
-	m[1][1] = m11
-	m[1][2] = m12
-	m[2][0] = m20
-	m[2][1] = m21
-	m[2][2] = m22
-}