[parser] Refactor preparser GetSymbol

R=adamk@chromium.org, marja@chromium.org
BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2256163002
Cr-Commit-Position: refs/heads/master@{#38738}

src/parsing/preparser.cc

@@ -58,38 +58,34 @@ void PreParserTraits::ReportMessageAt(Scanner::Location location,
 
 
 PreParserIdentifier PreParserTraits::GetSymbol(Scanner* scanner) {
-  if (scanner->current_token() == Token::ENUM) {
+  switch (scanner->current_token()) {
+    case Token::ENUM:
       return PreParserIdentifier::Enum();
-  } else if (scanner->current_token() == Token::AWAIT) {
+    case Token::AWAIT:
       return PreParserIdentifier::Await();
-  } else if (scanner->current_token() ==
-             Token::FUTURE_STRICT_RESERVED_WORD) {
+    case Token::FUTURE_STRICT_RESERVED_WORD:
       return PreParserIdentifier::FutureStrictReserved();
-  } else if (scanner->current_token() == Token::LET) {
+    case Token::LET:
       return PreParserIdentifier::Let();
-  } else if (scanner->current_token() == Token::STATIC) {
+    case Token::STATIC:
       return PreParserIdentifier::Static();
-  } else if (scanner->current_token() == Token::YIELD) {
+    case Token::YIELD:
       return PreParserIdentifier::Yield();
-  } else if (scanner->current_token() == Token::ASYNC) {
+    case Token::ASYNC:
       return PreParserIdentifier::Async();
-  }
-  if (scanner->UnescapedLiteralMatches("eval", 4)) {
+    default:
+      if (scanner->UnescapedLiteralMatches("eval", 4))
         return PreParserIdentifier::Eval();
-  }
-  if (scanner->UnescapedLiteralMatches("arguments", 9)) {
+      if (scanner->UnescapedLiteralMatches("arguments", 9))
         return PreParserIdentifier::Arguments();
-  }
-  if (scanner->UnescapedLiteralMatches("undefined", 9)) {
+      if (scanner->UnescapedLiteralMatches("undefined", 9))
         return PreParserIdentifier::Undefined();
-  }
-  if (scanner->LiteralMatches("prototype", 9)) {
+      if (scanner->LiteralMatches("prototype", 9))
         return PreParserIdentifier::Prototype();
-  }
-  if (scanner->LiteralMatches("constructor", 11)) {
+      if (scanner->LiteralMatches("constructor", 11))
         return PreParserIdentifier::Constructor();
-  }
       return PreParserIdentifier::Default();
+  }
 }