VM: Speed up output of UTF8 for 1-byte strings.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index bb9334f92b4849e3ff4e40c8f7934707bfc5d433..d44ccb84d6ba9496209ba9034752084fabcacb51 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -21209,29 +21209,7 @@ RawString* String::SubString(Thread* thread,
 
 
 const char* String::ToCString() const {
-  if (IsOneByteString()) {
-    // Quick conversion if OneByteString contains only ASCII characters.
-    intptr_t len = Length();
-    if (len == 0) {
-      return "";
-    }
-    Zone* zone = Thread::Current()->zone();
-    uint8_t* result = zone->Alloc<uint8_t>(len + 1);
-    NoSafepointScope no_safepoint;
-    const uint8_t* original_str = OneByteString::CharAddr(*this, 0);
-    for (intptr_t i = 0; i < len; i++) {
-      if (original_str[i] <= Utf8::kMaxOneByteChar) {
-        result[i] = original_str[i];
-      } else {
-        len = -1;
-        break;
-      }
-    }
-    if (len > 0) {
-      result[len] = 0;
-      return reinterpret_cast<const char*>(result);
-    }
-  }
+  NoSafepointScope no_safepoint;
   const intptr_t len = Utf8::Length(*this);
   Zone* zone = Thread::Current()->zone();
   uint8_t* result = zone->Alloc<uint8_t>(len + 1);