Revert "[vm] Only call .hashCode once when adding to Map and Set"

This reverts commit 438c1ed.

Reason for revert: b/231617607 and b/230945329.
Will reland after b/230945329 is addressed.

Original change's description:
> [vm] Only call `.hashCode` once when adding to `Map` and `Set`
>
> The methods to add to hash maps and hash sets are recursive: if the
> index needs to be rehashed then the same method is called again after
> rehashing.
>
> This CL nests the actual implementation in a private method that takes
> the full hashCode as an extra argument.
>
> No significant code size or run time changes are reported on our
> benchmarks. (Our benchmarks do not contain purposefully slow hashCodes.)
>
> Note that hashCode can be called again later if rehashing of the index
> is required on adding subsequent elements.
>
> Bug: #48948
> Change-Id: Ia3ccff9e592d675b4922ac78c4aa7ee0287ecb50
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/243623
> Reviewed-by: Martin Kustermann <kustermann@google.com>
> Commit-Queue: Daco Harkes <dacoharkes@google.com>

TBR=kustermann@google.com,dacoharkes@google.com

Change-Id: I214251b65ea89e7f729564a125e226f2e6d580c0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: #48948
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/243900
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>

sdk/lib/_internal/vm/lib/compact_hash.dart

@@ -345,6 +345,7 @@ mixin _ImmutableLinkedHashMapMixin<K, V>
 
     for (int j = 0; j < _usedData; j += 2) {
       final key = _data[j];
+      final value = _data[j + 1];
 
       final fullHash = _hashCode(key);
       final hashPattern = _HashBase._hashPattern(fullHash, hashMask, size);
@@ -451,10 +452,10 @@ mixin _LinkedHashMapMixin<K, V> on _HashBase, _EqualsAndHashCode {
     }
   }
 
-  void _insert(K key, V value, int fullHash, int hashPattern, int i) {
+  void _insert(K key, V value, int hashPattern, int i) {
     if (_usedData == _data.length) {
       _rehash();
-      _set(key, value, fullHash);
+      this[key] = value;
     } else {
       assert(1 <= hashPattern && hashPattern < (1 << 32));
       final int index = _usedData >> 1;
@@ -495,20 +496,16 @@ mixin _LinkedHashMapMixin<K, V> on _HashBase, _EqualsAndHashCode {
   }
 
   void operator []=(K key, V value) {
-    final int fullHash = _hashCode(key);
-    _set(key, value, fullHash);
-  }
-
-  void _set(K key, V value, int fullHash) {
     final int size = _index.length;
+    final int fullHash = _hashCode(key);
     final int hashPattern = _HashBase._hashPattern(fullHash, _hashMask, size);
     final int d =
         _findValueOrInsertPoint(key, fullHash, hashPattern, size, _index);
     if (d > 0) {
       _data[d] = value;
     } else {
       final int i = -d;
-      _insert(key, value, fullHash, hashPattern, i);
+      _insert(key, value, hashPattern, i);
     }
   }
 
@@ -529,7 +526,7 @@ mixin _LinkedHashMapMixin<K, V> on _HashBase, _EqualsAndHashCode {
       this[key] = value;
     } else {
       final int i = -d;
-      _insert(key, value, fullHash, hashPattern, i);
+      _insert(key, value, hashPattern, i);
     }
     return value;
   }
@@ -838,14 +835,10 @@ mixin _LinkedHashSetMixin<E> on _HashBase, _EqualsAndHashCode {
   }
 
   bool add(E key) {
-    final int fullHash = _hashCode(key);
-    return _add(key, fullHash);
-  }
-
-  bool _add(E key, int fullHash) {
     final int size = _index.length;
     final int sizeMask = size - 1;
     final int maxEntries = size >> 1;
+    final int fullHash = _hashCode(key);
     final int hashPattern = _HashBase._hashPattern(fullHash, _hashMask, size);
     int i = _HashBase._firstProbe(fullHash, sizeMask);
     int firstDeleted = -1;
@@ -866,7 +859,7 @@ mixin _LinkedHashSetMixin<E> on _HashBase, _EqualsAndHashCode {
     }
     if (_usedData == _data.length) {
       _rehash();
-      _add(key, fullHash);
+      add(key);
     } else {
       final int insertionPoint = (firstDeleted >= 0) ? firstDeleted : i;
       assert(1 <= hashPattern && hashPattern < (1 << 32));