Editorial: Eliminate 6 <p> elements that say when to apply early error rules

[jmdyck]

Normally, an early error rule consists of:

• an <emu-grammar> (with 1 or more productions), and
• a <ul> (with 1 or more "it is a Syntax Error" or "must cover" statements).

However, in a few cases, there is also a <p> that says when the rule is applied.

One such case is in 13.2.5.1, which PR #3227 will eliminate. This PR eliminates the remaining cases. These occur in 13.15.1, 13.15.5.1, and 14.7.5.1, and are all of the form:

<emu-grammar>
  (1 or more productions involving LeftHandSideExpression)
</emu-grammar>
<p>If |LeftHandSideExpression| is either an |ObjectLiteral| or
   an |ArrayLiteral|, the following Early Error rules are applied:</p>
<ul>
  <li>
    |LeftHandSideExpression| must cover an |AssignmentPattern|.
  </li>
</ul>
<p>If |LeftHandSideExpression| is neither an |ObjectLiteral| nor
     an |ArrayLiteral|, the following Early Error rule is applied:</p>
<ul>
  <li>
    It is a Syntax Error if AssignmentTargetType of
      |LeftHandSideExpression| is not ~simple~.
  </li>
</ul>

This PR takes each <p> and 'inlines' it into the subsequent <li>. (And then fuses the two <ul>.)