Fix bit field access for 64-bit big-endian architectures.

Need to use the kBitFieldSlot rather than kBitFieldOffset for
pointer-sized memory accesses.

(Fix for "[Atomics] code stubs for atomic operations")

R=bmeurer@chromium.org, binji@chromium.org, jarin@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1914463003

Cr-Commit-Position: refs/heads/master@{#35767}

src/builtins.cc

@@ -5202,7 +5202,7 @@ void ValidateSharedTypedArray(CodeStubAssembler* a, compiler::Node* tagged,
   a->Bind(&is_typed_array);
   Node* array_buffer = a->LoadObjectField(tagged, JSTypedArray::kBufferOffset);
   Node* is_buffer_shared = a->BitFieldDecode<JSArrayBuffer::IsShared>(
-      a->LoadObjectField(array_buffer, JSArrayBuffer::kBitFieldOffset));
+      a->LoadObjectField(array_buffer, JSArrayBuffer::kBitFieldSlot));
   a->Branch(is_buffer_shared, &is_shared, &not_shared);
   a->Bind(&not_shared);
   a->Goto(&invalid);