Add tests for Math constants

Closes gh-540

Because the specific value of each constant is specified as a
host-defined approximation, only the value type may be enforced by
Test262.

test/built-ins/Math/E/value.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Math.E is a numeric value
+esid: sec-math.e
+es6id: 20.2.1.1
+info: >
+    The Number value for e, the base of the natural logarithms, which is
+    approximately 2.7182818284590452354.
+
+    The precision of this approximation is host-defined.
+---*/
+
+assert.sameValue(typeof Math.E, 'number');
+assert.notSameValue(Math.E, NaN);

test/built-ins/Math/LN10/value.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Math.LN10 is a numeric value
+esid: sec-math.ln10
+es6id: 20.2.1.2
+info: >
+    The Number value for the natural logarithm of 10, which is approximately
+    2.302585092994046.
+
+    The precision of this approximation is host-defined.
+---*/
+
+assert.sameValue(typeof Math.LN10, 'number');
+assert.notSameValue(Math.LN10, NaN);

test/built-ins/Math/LN2/value.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Math.LN2 is a numeric value
+esid: sec-math.ln2
+es6id: 20.2.1.3
+info: >
+    The Number value for the natural logarithm of 2, which is approximately
+    0.6931471805599453.
+
+    The precision of this approximation is host-defined.
+---*/
+
+assert.sameValue(typeof Math.LN2, 'number');
+assert.notSameValue(Math.LN2, NaN);

test/built-ins/Math/LOG10E/value.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Math.LOG10E is a numeric value
+esid: sec-math.log10e
+es6id: 20.2.1.4
+info: >
+    The Number value for the base-10 logarithm of e, the base of the natural
+    logarithms; this value is approximately 0.4342944819032518.
+
+    The precision of this approximation is host-defined.
+---*/
+
+assert.sameValue(typeof Math.LOG10E, 'number');
+assert.notSameValue(Math.LOG10E, NaN);

test/built-ins/Math/LOG2E/value.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Math.LOG2E is a numeric value
+esid: sec-math.log2e
+es6id: 20.2.1.5
+info: >
+    The Number value for the base-2 logarithm of e, the base of the natural
+    logarithms; this value is approximately 1.4426950408889634.
+
+    The precision of this approximation is host-defined.
+---*/
+
+assert.sameValue(typeof Math.LOG2E, 'number');
+assert.notSameValue(Math.LOG2E, NaN);

test/built-ins/Math/PI/value.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Math.PI is a numeric value
+esid: sec-math.pi
+es6id: 20.2.1.6
+info: >
+    The Number value for pi, the ratio of the circumference of a circle to its
+    diameter, which is approximately 3.1415926535897932.
+
+    The precision of this approximation is host-defined.
+---*/
+
+assert.sameValue(typeof Math.PI, 'number');
+assert.notSameValue(Math.PI, NaN);

test/built-ins/Math/SQRT1_2/value.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Math.SQRT1_2 is a numeric value
+esid: sec-math.sqrt1_2
+es6id: 20.2.1.7
+info: >
+    The Number value for the square root of `1/2`, which is approximately
+    0.7071067811865476.
+
+    The precision of this approximation is host-defined.
+---*/
+
+assert.sameValue(typeof Math.SQRT1_2, 'number');
+assert.notSameValue(Math.SQRT1_2, NaN);

test/built-ins/Math/SQRT2/value.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Math.SQRT2 is a numeric value
+esid: sec-math.sqrt2
+es6id: 20.2.1.8
+info: >
+    The Number value for the square root of 2, which is approximately
+    1.4142135623730951.
+
+    The precision of this approximation is host-defined.
+---*/
+
+assert.sameValue(typeof Math.SQRT2, 'number');
+assert.notSameValue(Math.SQRT2, NaN);