Simplify the inserted scripts

We can assume that there are no text nodes before the template tag so this
simplifies the script that finds the comment node. It should be the direct
previous child.

Author: sebmarkbage

packages/react-dom/src/server/ReactDOMServerFormatConfig.js

@@ -1543,19 +1543,14 @@ export function writeEndSegment(
 //
 // function clientRenderBoundary(suspenseBoundaryID) {
 //   // Find the fallback's first element.
-//   let suspenseNode = document.getElementById(suspenseBoundaryID);
-//   if (!suspenseNode) {
+//   const suspenseIdNode = document.getElementById(suspenseBoundaryID);
+//   if (!suspenseIdNode) {
 //     // The user must have already navigated away from this tree.
 //     // E.g. because the parent was hydrated.
 //     return;
 //   }
-//   // Find the boundary around the fallback. This might include text nodes.
-//   do {
-//     suspenseNode = suspenseNode.previousSibling;
-//   } while (
-//     suspenseNode.nodeType !== COMMENT_NODE ||
-//     suspenseNode.data !== SUSPENSE_PENDING_START_DATA
-//   );
+//   // Find the boundary around the fallback. This is always the previous node.
+//   const suspenseNode = suspenseIdNode.previousSibling;
 //   // Tag it to be client rendered.
 //   suspenseNode.data = SUSPENSE_FALLBACK_START_DATA;
 //   // Tell React to retry it if the parent already hydrated.
@@ -1566,24 +1561,19 @@ export function writeEndSegment(
 //
 // function completeBoundary(suspenseBoundaryID, contentID) {
 //   // Find the fallback's first element.
-//   let suspenseNode = document.getElementById(suspenseBoundaryID);
+//   const suspenseIdNode = document.getElementById(suspenseBoundaryID);
 //   const contentNode = document.getElementById(contentID);
 //   // We'll detach the content node so that regardless of what happens next we don't leave in the tree.
 //   // This might also help by not causing recalcing each time we move a child from here to the target.
 //   contentNode.parentNode.removeChild(contentNode);
-//   if (!suspenseNode) {
+//   if (!suspenseIdNode) {
 //     // The user must have already navigated away from this tree.
 //     // E.g. because the parent was hydrated. That's fine there's nothing to do
 //     // but we have to make sure that we already deleted the container node.
 //     return;
 //   }
-//   // Find the boundary around the fallback. This might include text nodes.
-//   do {
-//     suspenseNode = suspenseNode.previousSibling;
-//   } while (
-//     suspenseNode.nodeType !== COMMENT_NODE ||
-//     suspenseNode.data !== SUSPENSE_PENDING_START_DATA
-//   );
+//   // Find the boundary around the fallback. This is always the previous node.
+//   const suspenseNode = suspenseIdNode.previousSibling;
 //
 //   // Clear all the existing children. This is complicated because
 //   // there can be embedded Suspense boundaries in the fallback.
@@ -1646,11 +1636,11 @@ export function writeEndSegment(
 // }
 
 const completeSegmentFunction =
-  'function $RS(b,f){var a=document.getElementById(b),c=document.getElementById(f);for(a.parentNode.removeChild(a);a.firstChild;)c.parentNode.insertBefore(a.firstChild,c);c.parentNode.removeChild(c)}';
+  'function $RS(a,b){a=document.getElementById(a);b=document.getElementById(b);for(a.parentNode.removeChild(a);a.firstChild;)b.parentNode.insertBefore(a.firstChild,b);b.parentNode.removeChild(b)}';
 const completeBoundaryFunction =
-  'function $RC(b,f){var a=document.getElementById(b),c=document.getElementById(f);c.parentNode.removeChild(c);if(a){do a=a.previousSibling;while(8!==a.nodeType||"$?"!==a.data);var h=a.parentNode,d=a.nextSibling,g=0;do{if(d&&8===d.nodeType){var e=d.data;if("/$"===e)if(0===g)break;else g--;else"$"!==e&&"$?"!==e&&"$!"!==e||g++}e=d.nextSibling;h.removeChild(d);d=e}while(d);for(;c.firstChild;)h.insertBefore(c.firstChild,d);a.data="$";a._reactRetry&&a._reactRetry()}}';
+  'function $RC(a,b){a=document.getElementById(a);b=document.getElementById(b);b.parentNode.removeChild(b);if(a){a=a.previousSibling;var f=a.parentNode,c=a.nextSibling,e=0;do{if(c&&8===c.nodeType){var d=c.data;if("/$"===d)if(0===e)break;else e--;else"$"!==d&&"$?"!==d&&"$!"!==d||e++}d=c.nextSibling;f.removeChild(c);c=d}while(c);for(;b.firstChild;)f.insertBefore(b.firstChild,c);a.data="$";a._reactRetry&&a._reactRetry()}}';
 const clientRenderFunction =
-  'function $RX(b){if(b=document.getElementById(b)){do b=b.previousSibling;while(8!==b.nodeType||"$?"!==b.data);b.data="$!";b._reactRetry&&b._reactRetry()}}';
+  'function $RX(a){if(a=document.getElementById(a))a=a.previousSibling,a.data="$!",a._reactRetry&&a._reactRetry()}';
 
 const completeSegmentScript1Full = stringToPrecomputedChunk(
   '<script>' + completeSegmentFunction + ';$RS("',