Add RegExp.prototype[@@matchall]

Additionally, modernize spec text generally

Closes tc39#2

spec.emu

@@ -1,47 +1,51 @@
-<link rel="stylesheet" href="./spec.css" />
-<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/8.4/styles/github.min.css" />
-<script src="./spec.js"></script>
 <pre class="metadata">
 title: String.prototype.matchAll
 stage: 1
 contributors: Jordan Harband
 </pre>
 <emu-clause id="String.prototype.matchAll">
 	<h1>String.prototype.matchAll ( _regexp_ )</h1>
-	<emu-note>_matchAll_ does not visibly mutate the provided _regexp_ in any way.</emu-note>
 	<p>When the _matchAll_ method is called, the following steps are taken:</p>
 	<emu-alg>
-		1. Let _O_ be RequireObjectCoercible(*this* value).
-		1. Let _isRegExp_ be IsRegExp(_regexp_).
-		1. ReturnIfAbrupt(_isRegExp_).
-		1. If _isRegExp_ is *false*, throw a *TypeError* exception.
-		1. Let _S_ be ToString(*O*).
-		1. ReturnIfAbrupt(_S_).
-		1. Let _flags_ be ToString(Get(regexp, *"flags"*)).
-		1. ReturnIfAbrupt(_flags_).
-		1. If _flags_ does not contain the character *"g"*, let _flags_ be the String concatenation of the String *"g"* and _flags_.
-		1. Let _rx_ be RegExpCreate(_regexp_, _flags_).
-		1. Let _lastIndex_ be ToLength(Get(regexp, *"lastIndex"*)).
+		1. Let _O_ be ? RequireObjectCoercible(*this* value).
+		1. If _regexp_ is neither *undefined* nor *null*, then
+			1. Let _matcher_ be ? GetMethod(_regexp_, @@matchAll).
+			1. If _matcher_ is not *undefined*, then
+				1. Return ? Call(_matcher_, _regexp_, &laquo; _O_ &raquo;).
+		1. Throw a *TypeError* exception.
+	</emu-alg>
+	<emu-note>Similarly to String.prototype.split, String.prototype.matchAll is designed to typically act without mutating its inputs.</emu-note>
+</emu-clause>
+
+<emu-clause id="RegExp.prototype[@@matchAll]">
+	<h1>RegExp.prototype [ @@matchAll ] ( _string_ )</h1>
+	<p>When the `@@matchAll` method is called, the following steps are taken:</p>
+	<emu-alg>
+		1. Let _rx_ be the *this* value.
+		1. If Type(_rx_) is not Object, throw a *TypeError* exception.
+		1. Let _S_ be ? ToString(_string_).
+		1. Let _C_ be ? SpeciesConstructor(_rx_, %RegExp%).
+		1. Let _flags_ be ? ToString(? Get(_rx_, `"flags"`)).
+		1. If _flags_ contains `"g"`, let _newFlags_ be _flags_.
+		1. Else, let _newFlags_ be the string that is the concatenation of _flags_ and `"g"`.
+		1. Let _matcher_ be ? Construct(_C_, &laquo; _rx_, _newFlags_ &raquo;).
+		1. Let _lastIndex_ be ToLength(Get(_rx_, *"lastIndex"*)).
 		1. ReturnIfAbrupt(_lastIndex_).
-		1. Let _setStatus_ be Set(_rx_, *"lastIndex"*, _lastIndex_, *true*).
+		1. Let _setStatus_ be Set(_matcher_, *"lastIndex"*, _lastIndex_, *true*).
 		1. ReturnIfAbrupt(_setStatus_).
-		1. Return CreateRegExpStringIterator(_rx_, _S_)
+		1. Return CreateRegExpStringIterator(_matcher_, _S_)
 	</emu-alg>
-	<p>The _length_ property of the _matchAll_ method is *1*.</p>
-	<emu-note>The _rx_ regular expression value is created solely to ensure that no visible mutation happens on _regexp_ - it should never be exposed to the environment.</emu-note>
 </emu-clause>
 
 <emu-clause id="CreateRegExpStringIterator">
 	<h1>CreateRegExpStringIterator( _regexp_, _string_ )</h1>
 
 	<p>The abstract operation CreateRegExpStringIterator is used to create such iterator objects. It performs the following steps:</p>
 	<emu-alg>
-		1. Assert: IsRegExp(_R_) is *true*.
-		1. Assert: ToBoolean(Get(_R_, *"global"*)) is *true*.
 		1. Assert: Type(_S_) is String.
-		1. Let _iterator_ be ObjectCreate(<emu-xref href="#%RegExpStringIteratorPrototype%">%RegExpStringIteratorPrototype%</emu-xref>, &laquo; [[IteratingRegExp]], [[IteratedString]] &raquo;).
-		1. Set _iterator's_ [[IteratingRegExp]] <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-object-internal-methods-and-internal-slots">internal slot</a> to _R_.
-		1. Set _iterator's_ [[IteratedString]] <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-object-internal-methods-and-internal-slots">internal slot</a> to _S_.
+		1. Let _iterator_ be ObjectCreate(<emu-xref href="#%RegExpStringIteratorPrototype%">%RegExpStringIteratorPrototype%</emu-xref>, «[[IteratingRegExp]], [[IteratedString]]»).
+		1. Set _iterator_.[[IteratingRegExp]] to _R_.
+		1. Set _iterator_.[[IteratedString]] to _S_.
 		1. Return _iterator_.
 	</emu-alg>
 </emu-clause>
@@ -57,15 +61,14 @@ contributors: Jordan Harband
 			1. Let _O_ be the *this* value.
 			1. If Type(_O_) is not Object, throw a *TypeError* exception.
 			1. If _O_ does not have all of the internal slots of a RegExp String Iterator Object Instance (see <emu-xref href="#PropertiesOfRegExpStringIteratorInstances"></emu-xref>), throw a *TypeError* exception.
-			1. Let _regexp_ be the value of the [[IteratingRegExp]] <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-object-internal-methods-and-internal-slots">internal slot</a> of _O_.
-			1. Let _string_ be the value of the [[IteratedString]] <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-object-internal-methods-and-internal-slots">internal slot</a> of _O_.
+			1. Let _regexp_ be _O_.[[IteratingRegExp]].
+			1. Let _string_ be _O_.[[IteratedString]].
 			1. Let _match_ be RegExpExec(_regexp_, _string_)
 			1. If _match_ is *null*, then
-				1. return CreateIterResultObject(*null*, *true*).
-			1. Else,
-				1. return CreateIterResultObject(_match_, *false*).
+				1. Return CreateIterResultObject(*null*, *true*).
+			1. Otherwise,
+				1. Return CreateIterResultObject(_match_, *false*).
 		</emu-alg>
-		<p>The _length_ property of the `next` method is *0*.</p>
 	</emu-clause>
 
 	<emu-clause id="%RegExpStringIteratorPrototype%[@@toStringTag]">