[interpreter] Reduce size of OSR nesting level field.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 510f4e93bff99d6a166bd902d3e06abcdd82a529..f627bd29f496ff0268e4becba3273305255f63be 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4570,10 +4570,8 @@ class BytecodeArray : public FixedArrayBase {
   static const int kFrameSizeOffset = kSourcePositionTableOffset + kPointerSize;
   static const int kParameterSizeOffset = kFrameSizeOffset + kIntSize;
   static const int kInterruptBudgetOffset = kParameterSizeOffset + kIntSize;
-  // TODO(4764): The OSR nesting level is guaranteed to be in [0;6] bounds and
-  // could potentially be merged with another field (e.g. parameter_size).
   static const int kOSRNestingLevelOffset = kInterruptBudgetOffset + kIntSize;
-  static const int kHeaderSize = kOSRNestingLevelOffset + kIntSize;
+  static const int kHeaderSize = kOSRNestingLevelOffset + kCharSize;
 
   // Maximal memory consumption for a single BytecodeArray.
   static const int kMaxSize = 512 * MB;