Provide polyfills for missing ES6 math functions

#KT-4900

Rename math.kt to js.math.kt

js/js.libraries/src/core/js.math.kt

@@ -1,6 +1,6 @@
 package kotlin.js
 
-//TODO: declare using number
+//TODO: deprecate
 /**
  * Exposes the JavaScript [Math object](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Math) to Kotlin.
  */
@@ -28,6 +28,31 @@ public external object Math {
     public fun round(value: Number): Int
     public fun floor(value: Number): Int
     public fun ceil(value: Number): Int
+
+    @PublishedApi
+    internal fun trunc(value: Number): Double
+    @PublishedApi
+    internal fun sign(value: Number): Double
+
+    @PublishedApi
+    internal fun sinh(value: Double): Double
+    @PublishedApi
+    internal fun cosh(value: Double): Double
+    @PublishedApi
+    internal fun tanh(value: Double): Double
+
+    @PublishedApi
+    internal fun hypot(x: Double, y: Double): Double
+
+    @PublishedApi
+    internal fun expm1(value: Double): Double
+
+    @PublishedApi
+    internal fun log10(value: Double): Double
+    @PublishedApi
+    internal fun log2(value: Double): Double
+    @PublishedApi
+    internal fun log1p(value: Double): Double
 }
 
 /**

js/js.libraries/src/js/polyfills.js

@@ -31,6 +31,79 @@ if (typeof String.prototype.endsWith === "undefined") {
         return lastIndex !== -1 && lastIndex === position;
     };
 }
+// ES6 Math polyfills
+if (typeof Math.sign === "undefined") {
+    Math.sign = function(x) {
+        x = +x; // convert to a number
+        if (x === 0 || isNaN(x)) {
+            return Number(x);
+        }
+        return x > 0 ? 1 : -1;
+    };
+}
+if (typeof Math.trunc === "undefined") {
+    Math.trunc = function(x) {
+        if (isNaN(x)) {
+            return NaN;
+        }
+        if (x > 0) {
+            return Math.floor(x);
+        }
+        return Math.ceil(x);
+    };
+}
+if (typeof Math.sinh === "undefined") {
+    Math.sinh = function(x) {
+        var y = Math.exp(x);
+        return (y - 1 / y) / 2;
+    };
+}
+if (typeof Math.cosh === "undefined") {
+    Math.cosh = function(x) {
+        var y = Math.exp(x);
+        return (y + 1 / y) / 2;
+    };
+}
+if (typeof Math.tanh === "undefined") {
+    Math.tanh = function(x){
+        var a = Math.exp(+x), b = Math.exp(-x);
+        return a == Infinity ? 1 : b == Infinity ? -1 : (a - b) / (a + b);
+    };
+}
+if (typeof Math.hypot === "undefined") {
+    Math.hypot = function() {
+        var y = 0;
+        var length = arguments.length;
+
+        for (var i = 0; i < length; i++) {
+            if (arguments[i] === Infinity || arguments[i] === -Infinity) {
+                return Infinity;
+            }
+            y += arguments[i] * arguments[i];
+        }
+        return Math.sqrt(y);
+    };
+}
+if (typeof Math.log10 === "undefined") {
+    Math.log10 = function(x) {
+        return Math.log(x) * Math.LOG10E;
+    };
+}
+if (typeof Math.log2 === "undefined") {
+    Math.log2 = function(x) {
+        return Math.log(x) * Math.LOG2E;
+    };
+}
+if (typeof Math.log1p === "undefined") {
+    Math.log1p = function(x) {
+        return Math.log(x + 1);
+    };
+}
+if (typeof Math.expm1 === "undefined") {
+    Math.expm1 = function(x) {
+        return Math.exp(x) - 1;
+    };
+}
 // For HtmlUnit and PhantomJs
 if (typeof ArrayBuffer.isView === "undefined") {
     ArrayBuffer.isView = function(a) {