[interpreter] Mark known immutable context slots as immutable

BUG=

Change-Id: I85f9619e0ecb7d0ebee9523e3b4c44ab7f091cfb
Reviewed-on: https://chromium-review.googlesource.com/451380Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43644}

src/interpreter/bytecode-generator.cc

@@ -2788,10 +2788,10 @@ void BytecodeGenerator::VisitDelete(UnaryOperation* expr) {
         builder()
             ->LoadContextSlot(execution_context()->reg(),
                               Context::NATIVE_CONTEXT_INDEX, 0,
-                              BytecodeArrayBuilder::kMutableSlot)
+                              BytecodeArrayBuilder::kImmutableSlot)
             .StoreAccumulatorInRegister(native_context)
             .LoadContextSlot(native_context, Context::EXTENSION_INDEX, 0,
-                             BytecodeArrayBuilder::kMutableSlot)
+                             BytecodeArrayBuilder::kImmutableSlot)
             .StoreAccumulatorInRegister(global_object)
             .LoadLiteral(variable->raw_name())
             .Delete(global_object, language_mode());
@@ -3342,17 +3342,17 @@ void BytecodeGenerator::VisitFunctionClosureForContext() {
     builder()
         ->LoadContextSlot(execution_context()->reg(),
                           Context::NATIVE_CONTEXT_INDEX, 0,
-                          BytecodeArrayBuilder::kMutableSlot)
+                          BytecodeArrayBuilder::kImmutableSlot)
         .StoreAccumulatorInRegister(native_context)
         .LoadContextSlot(native_context, Context::CLOSURE_INDEX, 0,
-                         BytecodeArrayBuilder::kMutableSlot);
+                         BytecodeArrayBuilder::kImmutableSlot);
   } else if (closure_scope()->is_eval_scope()) {
     // Contexts created by a call to eval have the same closure as the
     // context calling eval, not the anonymous closure containing the eval
     // code. Fetch it from the context.
     builder()->LoadContextSlot(execution_context()->reg(),
                                Context::CLOSURE_INDEX, 0,
-                               BytecodeArrayBuilder::kMutableSlot);
+                               BytecodeArrayBuilder::kImmutableSlot);
   } else {
     DCHECK(closure_scope()->is_function_scope() ||
            closure_scope()->is_module_scope());

test/cctest/interpreter/bytecode_expectations/GlobalDelete.golden

@@ -71,9 +71,9 @@ parameter count: 1
 bytecode array length: 16
 bytecodes: [
   /*   32 E> */ B(StackCheck),
-  /*   39 S> */ B(LdaCurrentContextSlot), U8(3),
+  /*   39 S> */ B(LdaImmutableCurrentContextSlot), U8(3),
                 B(Star), R(0),
-                B(LdaContextSlot), R(0), U8(2), U8(0),
+                B(LdaImmutableContextSlot), R(0), U8(2), U8(0),
                 B(Star), R(1),
                 B(LdaConstant), U8(0),
                 B(DeletePropertySloppy), R(1),
@@ -98,9 +98,9 @@ parameter count: 1
 bytecode array length: 16
 bytecodes: [
   /*   18 E> */ B(StackCheck),
-  /*   25 S> */ B(LdaCurrentContextSlot), U8(3),
+  /*   25 S> */ B(LdaImmutableCurrentContextSlot), U8(3),
                 B(Star), R(0),
-                B(LdaContextSlot), R(0), U8(2), U8(0),
+                B(LdaImmutableContextSlot), R(0), U8(2), U8(0),
                 B(Star), R(1),
                 B(LdaConstant), U8(0),
                 B(DeletePropertySloppy), R(1),