Normalize UriData.parse result.

sdk/lib/internal/internal.dart

Index: sdk/lib/internal/internal.dart
diff --git a/sdk/lib/internal/internal.dart b/sdk/lib/internal/internal.dart
index 0acf068b50b01a90b95843f6ca01893aeaae40b5..2ff80da9c4159781f5968e885dbafdd721ad0cfe 100644
--- a/sdk/lib/internal/internal.dart
+++ b/sdk/lib/internal/internal.dart
@@ -69,3 +69,30 @@ class ExternalName {
   final String name;
   const ExternalName(this.name);
 }
+
+// Shared hex-parsing utilities.
+
+/// Parses a single hex-digit as code unit.
+///
+/// Returns a negative value if the character is not a valid hex-digit.
+int hexDigitValue(int char) {
+  assert(char >= 0 && char <= 0xFFFF);
+  const int digit0 = 0x30;
+  const int a = 0x61;
+  const int f = 0x66;
+  int digit = char ^ digit0;
+  if (digit <= 9) return digit;
+  int letter = (char | 0x20);
+  if (a <= letter && letter <= f) return letter - (a - 10);
+  return -1;
+}
+
+/// Parses two hex digits in a string.
+///
+/// Returns a negative value if either digit isn't valid.
+int parseHexByte(String source, int index) {
+  assert(index + 2 <= source.length);
+  int digit1 = hexDigitValue(source.codeUnitAt(index));
+  int digit2 = hexDigitValue(source.codeUnitAt(index + 1));
+  return digit1 * 16 + digit2 - (digit2 & 256);
+}