Pixels class prototype and test (not to be committed).

runtime/vm/scanner.cc

Index: runtime/vm/scanner.cc
diff --git a/runtime/vm/scanner.cc b/runtime/vm/scanner.cc
index f7ae4ac59525fca9ca450cce9d6fa356af548dbb..7bbf8e7c3316dac24ae8b1fd4ae5693c2c29fccd 100644
--- a/runtime/vm/scanner.cc
+++ b/runtime/vm/scanner.cc
@@ -344,9 +344,10 @@ void Scanner::ScanIdentChars(bool allow_dollar) {
 }
 
 
-// Parse integer or double number literal of format:
-// NUMBER = INTEGER | DOUBLE
+// Parse integer, rational, or double number literal of format:
+// NUMBER = INTEGER | PIXELS | DOUBLE
 // INTEGER = D+ | (("0x" | "0X") H+)
+// PIXELS = ((D+ ["." D*]) | ("." D+)) ("px" | "PX")
 // DOUBLE = ((D+ ["." D*]) | ("." D+)) [ EXPONENT ]
 // EXPONENT = ("e" | "E") ["+" | "-"] D+
 void Scanner::ScanNumber(bool dec_point_seen) {
@@ -388,6 +389,12 @@ void Scanner::ScanNumber(bool dec_point_seen) {
       while (IsDecimalDigit(c0_)) {
         ReadChar();
       }
+    } else if ((c0_ == 'p') && (LookaheadChar(1) == 'x')) {
+      ReadChar();
+      Recognize(Token::kPIXELS);
+    } else if ((c0_ == 'P') && (LookaheadChar(1) == 'X')) {
+      ReadChar();
+      Recognize(Token::kPIXELS);
     }
   }
   if (current_token_.kind != Token::kILLEGAL) {