Make the condition for when this is predeclared easier to understand.

Just always predeclare it

R=marja@chromium.org,verwaest@chromium.org
BUG=v8:5215

Review-Url: https://codereview.chromium.org/2298743002
Cr-Commit-Position: refs/heads/master@{#39048}

src/ast/scopes.cc

@@ -129,12 +129,18 @@ Scope::Snapshot::Snapshot(Scope* scope)
       top_local_(scope->GetClosureScope()->locals_.length()),
       top_decl_(scope->GetClosureScope()->decls_.length()) {}
 
-DeclarationScope::DeclarationScope(Zone* zone)
+DeclarationScope::DeclarationScope(Zone* zone,
+                                   AstValueFactory* ast_value_factory)
     : Scope(zone),
       function_kind_(kNormalFunction),
       params_(4, zone),
       sloppy_block_function_map_(zone) {
+  DCHECK_EQ(scope_type_, SCRIPT_SCOPE);
   SetDefaults();
+
+  // Make sure that if we don't find the global 'this', it won't be declared as
+  // a regular dynamic global by predeclaring it with the right variable kind.
+  DeclareDynamicGlobal(ast_value_factory->this_string(), Variable::THIS);
 }
 
 DeclarationScope::DeclarationScope(Zone* zone, Scope* outer_scope,
@@ -144,6 +150,7 @@ DeclarationScope::DeclarationScope(Zone* zone, Scope* outer_scope,
       function_kind_(function_kind),
       params_(4, zone),
       sloppy_block_function_map_(zone) {
+  DCHECK_NE(scope_type, SCRIPT_SCOPE);
   SetDefaults();
   asm_function_ = outer_scope_->IsAsmModule();
 }
@@ -182,6 +189,7 @@ DeclarationScope::DeclarationScope(Zone* zone, ScopeType scope_type,
       function_kind_(scope_info->function_kind()),
       params_(0, zone),
       sloppy_block_function_map_(zone) {
+  DCHECK_NE(scope_type, SCRIPT_SCOPE);
   SetDefaults();
 }
 
@@ -420,13 +428,6 @@ void DeclarationScope::Analyze(ParseInfo* info, AnalyzeMode mode) {
          scope->outer_scope()->scope_type() == SCRIPT_SCOPE ||
          scope->outer_scope()->already_resolved_);
 
-  // If there's a chance that there's a reference to global 'this', predeclare
-  // it as a dynamic global on the script scope.
-  if (scope->GetReceiverScope()->is_script_scope()) {
-    info->script_scope()->DeclareDynamicGlobal(
-        info->ast_value_factory()->this_string(), Variable::THIS);
-  }
-
   scope->AllocateVariables(info, mode);
 
 #ifdef DEBUG

src/ast/scopes.h

@@ -587,7 +587,7 @@ class DeclarationScope : public Scope {
   DeclarationScope(Zone* zone, ScopeType scope_type,
                    Handle<ScopeInfo> scope_info);
   // Creates a script scope.
-  explicit DeclarationScope(Zone* zone);
+  DeclarationScope(Zone* zone, AstValueFactory* ast_value_factory);
 
   bool IsDeclaredParameter(const AstRawString* name) {
     // If IsSimpleParameterList is false, duplicate parameters are not allowed,

src/parsing/parser-base.h

@@ -667,7 +667,7 @@ class ParserBase {
   };
 
   DeclarationScope* NewScriptScope() const {
-    return new (zone()) DeclarationScope(zone());
+    return new (zone()) DeclarationScope(zone(), ast_value_factory());
   }
 
   DeclarationScope* NewVarblockScope() const {

test/cctest/test-parsing.cc

@@ -3321,7 +3321,8 @@ TEST(SerializationOfMaybeAssignmentFlag) {
   const i::AstRawString* name = avf.GetOneByteString("result");
   i::Handle<i::String> str = name->string();
   CHECK(str->IsInternalizedString());
-  i::DeclarationScope* script_scope = new (&zone) i::DeclarationScope(&zone);
+  i::DeclarationScope* script_scope =
+      new (&zone) i::DeclarationScope(&zone, &avf);
   i::Scope* s = i::Scope::DeserializeScopeChain(
       isolate, &zone, context, script_scope, &avf,
       i::Scope::DeserializationMode::kKeepScopeInfo);
@@ -3368,7 +3369,8 @@ TEST(IfArgumentsArrayAccessedThenParametersMaybeAssigned) {
   i::AstValueFactory avf(&zone, isolate->heap()->HashSeed());
   avf.Internalize(isolate);
 
-  i::DeclarationScope* script_scope = new (&zone) i::DeclarationScope(&zone);
+  i::DeclarationScope* script_scope =
+      new (&zone) i::DeclarationScope(&zone, &avf);
   i::Scope* s = i::Scope::DeserializeScopeChain(
       isolate, &zone, context, script_scope, &avf,
       i::Scope::DeserializationMode::kKeepScopeInfo);