2/n splitting PR #1828: updating removeRangeFromContentState (#1828)

Summary:
Splitting this PR into smaller pieces and updating them.

This chunk just makes some improvements/fixes to the removeRangeFromContentState
logic that handles nested blocks.

This is directly taken from mitermayer 's fork, props to him
Pull Request resolved: #1828

Reviewed By: mitermayer

Differential Revision: D9181963

Pulled By: mitermayer

fbshipit-source-id: 98abba5ed76ed00207aafc59afe940dd2eeb3d00

Author: mitermayer

src/model/transaction/removeRangeFromContentState.js

@@ -152,16 +152,16 @@ const updateBlockMapLinks = (
     // update start block if its retained
     transformBlock(startBlock.getKey(), blocks, block =>
       block.merge({
-        nextSibling: getNextValidSibling(startBlock, blocks, originalBlockMap),
-        prevSibling: getPrevValidSibling(startBlock, blocks, originalBlockMap),
+        nextSibling: getNextValidSibling(block, blocks, originalBlockMap),
+        prevSibling: getPrevValidSibling(block, blocks, originalBlockMap),
       }),
     );
 
     // update endblock if its retained
     transformBlock(endBlock.getKey(), blocks, block =>
       block.merge({
-        nextSibling: getNextValidSibling(endBlock, blocks, originalBlockMap),
-        prevSibling: getPrevValidSibling(endBlock, blocks, originalBlockMap),
+        nextSibling: getNextValidSibling(block, blocks, originalBlockMap),
+        prevSibling: getPrevValidSibling(block, blocks, originalBlockMap),
       }),
     );
 
@@ -186,14 +186,14 @@ const updateBlockMapLinks = (
     // update start block prev
     transformBlock(startBlock.getPrevSiblingKey(), blocks, block =>
       block.merge({
-        nextSibling: getNextValidSibling(startBlock, blocks, originalBlockMap),
+        nextSibling: getNextValidSibling(block, blocks, originalBlockMap),
       }),
     );
 
     // update end block next
     transformBlock(endBlock.getNextSiblingKey(), blocks, block =>
       block.merge({
-        prevSibling: getPrevValidSibling(endBlock, blocks, originalBlockMap),
+        prevSibling: getPrevValidSibling(block, blocks, originalBlockMap),
       }),
     );