Allow flags strings in quotes.

src/flags.cc

Index: src/flags.cc
diff --git a/src/flags.cc b/src/flags.cc
index 8e42206c59922ddad20c4422d7b7b718f20a833d..717bf55b7c9a1a8b386c0a66ab33900774a020a8 100644
--- a/src/flags.cc
+++ b/src/flags.cc
@@ -499,6 +499,12 @@ static char* SkipBlackSpace(char* p) {
 
 // static
 int FlagList::SetFlagsFromString(const char* str, int len) {
+  // The string might be in quotes. Skip the quotes.
+  if (len >= 2 && (str[0] == '\'' || str[0] == '"') && str[0] == str[len - 1]) {
+    ++str;
+    len -= 2;
+  }
+
   // make a 0-terminated copy of str
   ScopedVector<char> copy0(len + 1);
   OS::MemCopy(copy0.start(), str, len);