Editorial: misc cleanups (#1300)

 - Editorial: drop annotations from non-def Async productions
    Mostly "[no LineTerminator here]", and a few "[lookahead != `{`]".
 - Editorial: swap order of RHSs in non-def productions
    ... so that they match the order of the corresponding RHSs in the defining production.
    (I think these were the only 2 places where this disorder occurred.)
 - Editorial: "_notifierEvent_" -> "_notifyEvent_" in NotifyWaiter
    because _notifierEvent_ isn't defined.
 - Editorial: merge two adjacent <emu-grammar> elements
    (It's the only such occurrence in the spec.)
    Merging them into a single element makes it easier
    to programmatically associate the following algorithm
    with both productions, rather than just the second.
 - Editorial: enforce space before param list in <h1>
 - Editorial: insert blank line between productions in a multi-production block.
 - Editorial: Delete annotations from 'use' productions
    (We almost never repeat gramatical annotations in non-defining productions.)
 - Editorial: change "Let" to "Set" in 3 places
 - Markup: Insert missing slash in end-tag
 - Editorial: Move 'Object.fromEntries' clause to its proper place in alphabetical order.
 - Editorial: Add underscores to parameter name
 - Markup: Use 'title' attribute in <emu-xref> element
    If we want the rendered text of a <emu-xref> element to be a clause-title,
    we usually just use the 'title' attribute. (Moreso in steps of this form.)
 - Editorial: add 'Return' for CreateDataPropertyOnObject
 - Editorial: Move 'Symbol.prototype.description' clause to its proper place in alphabetical order.
 - Editorial: delete extra space
 - Editorial: Change "a String value" to "the String value" since it's uniquely determined.
 - Editorial: Change "a code unit" to "the code unit" since it's uniquely determined.
 - Editorial: Change "or" to "or if"
    (In cases like this, we repeat the "if".)
 - Markup: Dissolve unnecessary <emu-xref>
    (The ecmarkup process will create the link automatically.)
 - Editorial: Fix some indentation
 - Editorial: Insert call to ReturnIfAbrupt
    ... because ClassDefinitionEvaluation can return abruptly.
 - Editorial: use 'string-concatentation'
 - Editorial: Change capitalization and xref target
    For "built-in Function object"...
    1) lower-case the "F", because we never use the capital in that phrase; and
    2) change the emu-xref target from
       `#sec-ecmascript-standard-built-in-objects` to `#sec-built-in-function-objects`
       because the former suggests that the phrase only refers to *standard* built-in functions,
       rather than *all* built-in functions.
 - Editorial: *name* -> `name`
    (We always use backticks for "the `name` property".)
 - Editorial: Insert "If Type(_func_) is Object and"
    ... because you shouldn't ask whether a value has a particular internal slot
    without first establishing that it's an object.
 - Markup: Add type="definition" to definition of NativeFunction