add Math.f16round

spec.html

@@ -3,7 +3,7 @@
 <pre class="metadata">
 title: Float16Array
 status: proposal
-stage: 1
+stage: 2
 copyright: false
 contributors: Kevin Gibbons
 </pre>
@@ -28,6 +28,22 @@ <h1><ins>Float16Array ( . . . )</ins></h1>
   </emu-clause>
 </emu-clause>
 
+<emu-clause id="sec-function-properties-of-the-math-object">
+  <h1>Function Properties of the Math Object</h1>
+  <emu-clause id="sec-math.f16round">
+    <h1><ins>Math.f16round ( _x_ )</ins></h1>
+    <p>This function performs the following steps when called:</p>
+    <emu-alg>
+      1. Let _n_ be ? ToNumber(_x_).
+      1. If _n_ is *NaN*, return *NaN*.
+      1. If _n_ is one of *+0*<sub>𝔽</sub>, *-0*<sub>𝔽</sub>, *+∞*<sub>𝔽</sub>, or *-∞*<sub>𝔽</sub>, return _n_.
+      1. Let _n16_ be the result of converting _n_ to a value in IEEE 754-2019 binary16 format using roundTiesToEven mode.
+      1. Let _n64_ be the result of converting _n16_ to a value in IEEE 754-2019 binary64 format.
+      1. Return the ECMAScript Number value corresponding to _n64_.
+    </emu-alg>
+  </emu-clause>
+</emu-clause>
+
 <emu-clause id="sec-typedarray-objects">
   <h1>TypedArray Objects</h1>
   <p>The table below is modified by the addition of a row for float16.</p>