[destructuring] Implement parameter pattern matching.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 39d0d9278b132fd4dfc5a9ebd104661f1f846205..78f2176cae9cf01d838e60a8eac824111e1630ee 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -751,6 +751,10 @@ class ParserTraits {
   ZoneList<v8::internal::Statement*>* NewStatementList(int size, Zone* zone) {
     return new(zone) ZoneList<v8::internal::Statement*>(size, zone);
   }
+
+  V8_INLINE void AddParameterInitializationBlock(
+      ZoneList<v8::internal::Statement*>* body, bool* ok);
+
   V8_INLINE Scope* NewScope(Scope* parent_scope, ScopeType scope_type,
                             FunctionKind kind = kNormalFunction);
 
@@ -1121,6 +1125,8 @@ class Parser : public ParserBase<ParserTraits> {
   PreParser::PreParseResult ParseLazyFunctionBodyWithPreParser(
       SingletonLogger* logger, Scanner::BookmarkScope* bookmark = nullptr);
 
+  Block* BuildParameterInitializationBlock(bool* ok);
+
   // Consumes the ending }.
   ZoneList<Statement*>* ParseEagerFunctionBody(
       const AstRawString* function_name, int pos, Variable* fvar,
@@ -1274,13 +1280,14 @@ void ParserTraits::DeclareFormalParameter(Scope* scope, Expression* pattern,
                                           ExpressionClassifier* classifier,
                                           bool is_rest) {
   bool is_duplicate = false;
-  if (!pattern->IsVariableProxy()) {
-    // TODO(dslomov): implement.
-    DCHECK(parser_->allow_harmony_destructuring());
-    return;
-  }
-  auto name = pattern->AsVariableProxy()->raw_name();
-  Variable* var = scope->DeclareParameter(name, VAR, is_rest, &is_duplicate);
+  bool is_simple_name = pattern->IsVariableProxy();
+  DCHECK(parser_->allow_harmony_destructuring() || is_simple_name);
+
+  const AstRawString* name = is_simple_name
+                                 ? pattern->AsVariableProxy()->raw_name()
+                                 : parser_->ast_value_factory()->empty_string();
+  Variable* var = scope->DeclareParameter(
+      name, is_simple_name ? nullptr : pattern, VAR, is_rest, &is_duplicate);
   if (is_sloppy(scope->language_mode())) {
     // TODO(sigurds) Mark every parameter as maybe assigned. This is a
     // conservative approximation necessary to account for parameters
@@ -1292,6 +1299,16 @@ void ParserTraits::DeclareFormalParameter(Scope* scope, Expression* pattern,
         parser_->scanner()->location());
   }
 }
+
+
+void ParserTraits::AddParameterInitializationBlock(
+    ZoneList<v8::internal::Statement*>* body, bool* ok) {
+  auto* init_block = parser_->BuildParameterInitializationBlock(ok);
+  if (!*ok) return;
+  if (init_block != nullptr) {
+    body->Add(init_block, parser_->zone());
+  }
+}
 } }  // namespace v8::internal
 
 #endif  // V8_PARSER_H_