Revert "Add some support for the code-point code-unit distinction."

runtime/vm/scanner.cc

Index: runtime/vm/scanner.cc
diff --git a/runtime/vm/scanner.cc b/runtime/vm/scanner.cc
index 52c7248102cf80d47e52da89eaff6e51fbbbf47d..54ae2bdd606c84492178b8e7a2212c9070ceeb2e 100644
--- a/runtime/vm/scanner.cc
+++ b/runtime/vm/scanner.cc
@@ -529,7 +529,7 @@ void Scanner::ScanEscapedCodePoint(uint32_t* code_point) {
 
 
 void Scanner::ScanLiteralStringChars(bool is_raw) {
-  GrowableArray<uint16_t> string_chars(64);
+  GrowableArray<uint32_t> string_chars(64);
 
   ASSERT(IsScanningString());
   // We are at the first character of a string literal piece. A string literal
@@ -565,15 +565,7 @@ void Scanner::ScanLiteralStringChars(bool is_raw) {
           break;
         case 'u':
         case 'x': {
-          uint32_t ch;
-          ScanEscapedCodePoint(&ch);
-          int32_t code_point = ch;
-          if (code_point > Utf16::kMaxCodeUnit) {
-            string_chars.Add(Utf16::LeadFromCodePoint(code_point));
-            escape_char = Utf16::TrailFromCodePoint(code_point);
-          } else {
-            escape_char = code_point;
-          }
+          ScanEscapedCodePoint(&escape_char);
           break;
         }
         default: