Editorial: Fix incorrect note in reduce and reduceRight. Closes #744.

spec.html

@@ -30578,7 +30578,7 @@ <h1>Array.prototype.push ( ..._items_ )</h1>
       <emu-clause id="sec-array.prototype.reduce">
         <h1>Array.prototype.reduce ( _callbackfn_ [ , _initialValue_ ] )</h1>
         <emu-note>
-          <p>_callbackfn_ should be a function that takes four arguments. `reduce` calls the callback, as a function, once for each element present in the array, in ascending order.</p>
+          <p>_callbackfn_ should be a function that takes four arguments. `reduce` calls the callback, as a function, once for each element after the first element present in the array, in ascending order.</p>
           <p>_callbackfn_ is called with four arguments: the _previousValue_ (value from the previous call to _callbackfn_), the _currentValue_ (value of the current element), the _currentIndex_, and the object being traversed. The first time that callback is called, the _previousValue_ and _currentValue_ can be one of two values. If an _initialValue_ was provided in the call to `reduce`, then _previousValue_ will be equal to _initialValue_ and _currentValue_ will be equal to the first value in the array. If no _initialValue_ was provided, then _previousValue_ will be equal to the first value in the array and _currentValue_ will be equal to the second. It is a *TypeError* if the array contains no elements and _initialValue_ is not provided.</p>
           <p>`reduce` does not directly mutate the object on which it is called but the object may be mutated by the calls to _callbackfn_.</p>
           <p>The range of elements processed by `reduce` is set before the first call to _callbackfn_. Elements that are appended to the array after the call to `reduce` begins will not be visited by _callbackfn_. If existing elements of the array are changed, their value as passed to _callbackfn_ will be the value at the time `reduce` visits them; elements that are deleted after the call to `reduce` begins and before being visited are not visited.</p>
@@ -30619,7 +30619,7 @@ <h1>Array.prototype.reduce ( _callbackfn_ [ , _initialValue_ ] )</h1>
       <emu-clause id="sec-array.prototype.reduceright">
         <h1>Array.prototype.reduceRight ( _callbackfn_ [ , _initialValue_ ] )</h1>
         <emu-note>
-          <p>_callbackfn_ should be a function that takes four arguments. `reduceRight` calls the callback, as a function, once for each element present in the array, in descending order.</p>
+          <p>_callbackfn_ should be a function that takes four arguments. `reduceRight` calls the callback, as a function, once for each element after the first element present in the array, in descending order.</p>
           <p>_callbackfn_ is called with four arguments: the _previousValue_ (value from the previous call to _callbackfn_), the _currentValue_ (value of the current element), the _currentIndex_, and the object being traversed. The first time the function is called, the _previousValue_ and _currentValue_ can be one of two values. If an _initialValue_ was provided in the call to `reduceRight`, then _previousValue_ will be equal to _initialValue_ and _currentValue_ will be equal to the last value in the array. If no _initialValue_ was provided, then _previousValue_ will be equal to the last value in the array and _currentValue_ will be equal to the second-to-last value. It is a *TypeError* if the array contains no elements and _initialValue_ is not provided.</p>
           <p>`reduceRight` does not directly mutate the object on which it is called but the object may be mutated by the calls to _callbackfn_.</p>
           <p>The range of elements processed by `reduceRight` is set before the first call to _callbackfn_. Elements that are appended to the array after the call to `reduceRight` begins will not be visited by _callbackfn_. If existing elements of the array are changed by _callbackfn_, their value as passed to _callbackfn_ will be the value at the time `reduceRight` visits them; elements that are deleted after the call to `reduceRight` begins and before being visited are not visited.</p>