Interpolated strings are never considered compile time const

tests/language/src/StringInterpolationTest.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Tests for string interpolation
 class StringInterpolationTest {
 
   StringInterpolationTest() {}
 
   static final int i = 1;
@@ skipping 16 matching lines @@
     var c4 = '4';
     // no chars before/after/between embedded expressions
     Expect.equals(" 1", " ${c1}");
     Expect.equals("1 ", "${c1} ");
     Expect.equals("1", "${c1}");
     Expect.equals("12", "${c1}${c2}");
     Expect.equals("12 34", "${c1}${c2} ${c3}${c4}");
 
     // embedding static fields
     Expect.equals(" hi 1 ", " hi ${i} ");
-    Expect.equals(true, " hi ${i} " === " hi ${i} ");
     Expect.equals(" hi <hi> ", " hi ${a} ");
 
     // embedding method parameters
     Expect.equals("param = 9", test.embedParams(9));
 
     // embedding a class field
     Expect.equals("j = 3", test.embedSingleField());
 
     // embedding more than one (non-constant) expression
     Expect.equals(" hi 1 <hi>", " hi ${i} ${a}");
@@ skipping 21 matching lines @@
   }
 
   String embedMultipleFields() {
     return "j = ${j}; k = ${k}";
   }
 }
 
 main() {
   StringInterpolationTest.testMain(false);
 }