Explain what is happening in 'isNumericName'.

src/compiler/checker.ts

@@ -4084,6 +4084,21 @@ module ts {
         }
 
         function isNumericName(name: string) {
+            // The intent of numeric names is that
+            //     - they are names with text in a numeric form, and that
+            //     - setting properties/indexing with them is always equivalent to doing so with the numeric literal 'numLit',
+            //         acquired by applying the abstract 'ToNumber' operation on the name's text.
+            //
+            // The subtlety is in the latter portion, as we cannot reliably say that anything that looks like a numeric literal is a numeric name.
+            // In fact, it is the case that the text of the name must be equal to 'ToString(numLit)' for this to hold.
+            //
+            // Consider the property name '"0xF00D"'. When one indexes with '0xF00D', they are actually indexing with the value of 'ToString(0xF00D)'
+            // according to the ECMAScript specification, so it is actually as if the user indexed with the string '"61453"'.
+            // Thus, the text of all numeric literals equivalent to '61543' such as '0xF00D', '0xf00D', '0170015', etc. are not valid numeric names
+            // because their 'ToString' representation is not equal to their original text.
+            // This is motivated by ECMA-262 sections 9.3.1, 9.8.1, 11.1.5, and 11.2.1.
+            //
+            // Here, we test whether 'ToString(ToNumber(name))' is exactly equal to 'name'.
             return (+name).toString() === name;
         }