[interpreter] Add a fast path for dynamic local load

src/interpreter/bytecode-array-builder.cc

Index: src/interpreter/bytecode-array-builder.cc
diff --git a/src/interpreter/bytecode-array-builder.cc b/src/interpreter/bytecode-array-builder.cc
index 5fc778d72476b4f612e555ecd2650ffe7ccd6531..fe334e16412933e6156099538a84c4139f128701 100644
--- a/src/interpreter/bytecode-array-builder.cc
+++ b/src/interpreter/bytecode-array-builder.cc
@@ -295,6 +295,18 @@ BytecodeArrayBuilder& BytecodeArrayBuilder::LoadLookupSlot(
   return *this;
 }
 
+BytecodeArrayBuilder& BytecodeArrayBuilder::LoadLookupContextSlot(
+    const Handle<String> name, TypeofMode typeof_mode, int slot_index,
+    int depth) {
+  Bytecode bytecode = (typeof_mode == INSIDE_TYPEOF)
+                          ? Bytecode::kLdaLookupContextSlotInsideTypeof
+                          : Bytecode::kLdaLookupContextSlot;
+  size_t name_index = GetConstantPoolEntry(name);
+  Output(bytecode, UnsignedOperand(name_index), UnsignedOperand(slot_index),
+         UnsignedOperand(depth));
+  return *this;
+}
+
 BytecodeArrayBuilder& BytecodeArrayBuilder::StoreLookupSlot(
     const Handle<String> name, LanguageMode language_mode) {
   Bytecode bytecode = BytecodeForStoreLookupSlot(language_mode);