Optimize typed-array length loading.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 5128ed32809ed0b56ac8b86aa600ead77a3a5ba1..5b91bb588887e821364ba63c5115867215c5eab3 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -5670,6 +5670,13 @@ class HObjectAccess V8_FINAL {
                 ? Representation::Smi() : Representation::Tagged());
   }
 
+  static HObjectAccess ForTypedArrayLength() {
+    return HObjectAccess(
+        kInobject,
+        JSTypedArray::kLengthOffset,
+        Representation::Tagged());
+  }
+
   static HObjectAccess ForAllocationSiteTransitionInfo() {
     return HObjectAccess(kInobject, AllocationSite::kTransitionInfoOffset);
   }