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/sprite/clock/tween.go

Index: third_party/go/src/golang.org/x/mobile/sprite/clock/tween.go
diff --git a/third_party/go/src/golang.org/x/mobile/sprite/clock/tween.go b/third_party/go/src/golang.org/x/mobile/sprite/clock/tween.go
deleted file mode 100644
index f5f2a038cb5fbabeadbe399fdcd84efb9d7c9733..0000000000000000000000000000000000000000
--- a/third_party/go/src/golang.org/x/mobile/sprite/clock/tween.go
+++ /dev/null
@@ -1,83 +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 clock
-
-// Standard tween functions.
-//
-// Easing means a slowing near the timing boundary, as defined by
-// a cubic bezier curve. Exact parameters match the CSS properties.
-var (
-	EaseIn    = CubicBezier(0.42, 0, 1, 1)
-	EaseOut   = CubicBezier(0, 0, 0.58, 1)
-	EaseInOut = CubicBezier(0.42, 0, 0.58, 1)
-)
-
-// Linear computes the fraction [0,1] that t lies between [t0,t1].
-func Linear(t0, t1, t Time) float32 {
-	if t >= t1 {
-		return 1
-	}
-	if t <= t0 {
-		return 0
-	}
-	return float32(t-t0) / float32(t1-t0)
-}
-
-// CubicBezier generates a tween function determined by a Cubic Bézier curve.
-//
-// The parameters are cubic control parameters. The curve starts at (0,0)
-// going toward (x0,y0), and arrives at (1,1) coming from (x1,y1).
-func CubicBezier(x0, y0, x1, y1 float32) func(t0, t1, t Time) float32 {
-	return func(start, end, now Time) float32 {
-		// A Cubic-Bezier curve restricted to starting at (0,0) and
-		// ending at (1,1) is defined as
-		//
-		// 	B(t) = 3*(1-t)^2*t*P0 + 3*(1-t)*t^2*P1 + t^3
-		//
-		// with derivative
-		//
-		//	B'(t) = 3*(1-t)^2*P0 + 6*(1-t)*t*(P1-P0) + 3*t^2*(1-P1)
-		//
-		// Given a value x ∈ [0,1], we solve for t using Newton's
-		// method and solve for y using t.
-
-		x := Linear(start, end, now)
-
-		// Solve for t using x.
-		t := x
-		for i := 0; i < 5; i++ {
-			t2 := t * t
-			t3 := t2 * t
-			d := 1 - t
-			d2 := d * d
-
-			nx := 3*d2*t*x0 + 3*d*t2*x1 + t3
-			dxdt := 3*d2*x0 + 6*d*t*(x1-x0) + 3*t2*(1-x1)
-			if dxdt == 0 {
-				break
-			}
-
-			t -= (nx - x) / dxdt
-			if t <= 0 || t >= 1 {
-				break
-			}
-		}
-		if t < 0 {
-			t = 0
-		}
-		if t > 1 {
-			t = 1
-		}
-
-		// Solve for y using t.
-		t2 := t * t
-		t3 := t2 * t
-		d := 1 - t
-		d2 := d * d
-		y := 3*d2*t*y0 + 3*d*t2*y1 + t3
-
-		return y
-	}
-}