Editorial: Simplify the 'Assertion' production

... by using 'QuantifiableAssertion' under [+U] too.
(This involves adding the [U] parameter to QuantifiableAssertion.)

spec.html

@@ -30941,7 +30941,7 @@ <h2>Patterns</h2>
           [+U] Assertion[+U, ?N]
           [+U] Atom[+U, ?N]
           [+U] Atom[+U, ?N] Quantifier
-          [~U] QuantifiableAssertion[?N] Quantifier
+          [~U] QuantifiableAssertion[~U, ?N] Quantifier
           [~U] Assertion[~U, ?N]
           [~U] ExtendedAtom[?N] Quantifier
           [~U] ExtendedAtom[?N]
@@ -30951,15 +30951,13 @@ <h2>Patterns</h2>
           `$`
           `\` `b`
           `\` `B`
-          [+U] `(` `?` `=` Disjunction[+U, ?N] `)`
-          [+U] `(` `?` `!` Disjunction[+U, ?N] `)`
-          [~U] QuantifiableAssertion[?N]
+          QuantifiableAssertion[?U, ?N]
           `(` `?` `&lt;=` Disjunction[?U, ?N] `)`
           `(` `?` `&lt;!` Disjunction[?U, ?N] `)`
 
-        QuantifiableAssertion[N] ::
-          `(` `?` `=` Disjunction[~U, ?N] `)`
-          `(` `?` `!` Disjunction[~U, ?N] `)`
+        QuantifiableAssertion[U, N] ::
+          `(` `?` `=` Disjunction[?U, ?N] `)`
+          `(` `?` `!` Disjunction[?U, ?N] `)`
 
         Quantifier ::
           QuantifierPrefix
@@ -31829,7 +31827,7 @@ <h1>Assertion</h1>
             1. If _a_ is *false* and _b_ is *true*, return *false*.
             1. Return *true*.
         </emu-alg>
-        <p>The production <emu-grammar>Assertion :: `(` `?` `=` Disjunction `)`</emu-grammar> evaluates as follows:</p>
+        <p>The production <emu-grammar>QuantifiableAssertion :: `(` `?` `=` Disjunction `)`</emu-grammar> evaluates as follows:</p>
         <emu-alg>
           1. Evaluate |Disjunction| with +1 as its _direction_ argument to obtain a Matcher _m_.
           1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps:
@@ -31842,7 +31840,7 @@ <h1>Assertion</h1>
             1. Let _z_ be the State (_xe_, _cap_).
             1. Call _c_(_z_) and return its result.
         </emu-alg>
-        <p>The production <emu-grammar>Assertion :: `(` `?` `!` Disjunction `)`</emu-grammar> evaluates as follows:</p>
+        <p>The production <emu-grammar>QuantifiableAssertion :: `(` `?` `!` Disjunction `)`</emu-grammar> evaluates as follows:</p>
         <emu-alg>
           1. Evaluate |Disjunction| with +1 as its _direction_ argument to obtain a Matcher _m_.
           1. Return an internal Matcher closure that takes two arguments, a State _x_ and a Continuation _c_, and performs the following steps:
@@ -31878,8 +31876,6 @@ <h1>Assertion</h1>
             1. If _r_ is not ~failure~, return ~failure~.
             1. Call _c_(_x_) and return its result.
         </emu-alg>
-        <p>----</p>
-        <p>The evaluation rules for the <emu-grammar>Assertion :: `(` `?` `=` Disjunction `)`</emu-grammar> and <emu-grammar>Assertion :: `(` `?` `!` Disjunction `)`</emu-grammar> productions are also used for the |QuantifiableAssertion| productions, but with |QuantifiableAssertion| substituted for |Assertion|.</p>
 
         <emu-clause id="sec-runtime-semantics-wordcharacters-abstract-operation" aoid="WordCharacters">
           <h1>Runtime Semantics: WordCharacters ( )</h1>