Allow specifying base offset when constructing Keyed hydrogen instructions

src/hydrogen-dehoist.cc

Index: src/hydrogen-dehoist.cc
diff --git a/src/hydrogen-dehoist.cc b/src/hydrogen-dehoist.cc
index 44aeb4887d024fc702d18c32e04b88865c52b0eb..e8008231ad3f22feaba64fbe9220bcd6c656a0ae 100644
--- a/src/hydrogen-dehoist.cc
+++ b/src/hydrogen-dehoist.cc
@@ -30,12 +30,13 @@ static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) {
   int32_t value = constant->Integer32Value() * sign;
   // We limit offset values to 30 bits because we want to avoid the risk of
   // overflows when the offset is added to the object header size.
-  if (value >= 1 << array_operation->MaxIndexOffsetBits() || value < 0) return;
+  if (value >= 1 << array_operation->MaxBaseOffsetBits() || value < 0) return;
   array_operation->SetKey(subexpression);
   if (binary_operation->HasNoUses()) {
     binary_operation->DeleteAndReplaceWith(NULL);
   }
-  array_operation->SetIndexOffset(static_cast<uint32_t>(value));
+  value <<= ElementsKindToShiftSize(array_operation->elements_kind());
+  array_operation->IncreaseBaseOffset(static_cast<uint32_t>(value));
   array_operation->SetDehoisted(true);
 }