Report RESULT_NUM when constant value is String + String.

editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/resolver/CompileTimeErrorCodeTest.java

Index: editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/resolver/CompileTimeErrorCodeTest.java
diff --git a/editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/resolver/CompileTimeErrorCodeTest.java b/editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/resolver/CompileTimeErrorCodeTest.java
index 428b73617ab9af9736c79e690595a2f2e8e1cffa..6d11c39a5e40cadcabd7e1750ac3ea504c58ddbf 100644
--- a/editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/resolver/CompileTimeErrorCodeTest.java
+++ b/editor/tools/plugins/com.google.dart.engine_test/src/com/google/dart/engine/resolver/CompileTimeErrorCodeTest.java
@@ -683,6 +683,13 @@ public class CompileTimeErrorCodeTest extends ResolverTestCase {
     check_constEvalTypeNum_withParameter_binary("p % ''");
   }
 
+  public void test_constEvalTypeNum_plus_String() throws Exception {
+    Source source = addSource("const C = 'a' + 'b';");
+    resolve(source);
+    assertErrors(CompileTimeErrorCode.CONST_EVAL_TYPE_NUM);
+    verify(source);
+  }
+
   public void test_constFormalParameter_fieldFormalParameter() throws Exception {
     Source source = addSource(createSource(//
         "class A {",
@@ -2498,7 +2505,7 @@ public class CompileTimeErrorCodeTest extends ResolverTestCase {
         "  const A(String p) : a = p && true;",
         "}"));
     resolve(source);
-    assertErrors(CompileTimeErrorCode.NON_CONSTANT_VALUE_IN_INITIALIZER);
+    assertErrors(CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL);
     verify(source);
   }
 
@@ -2509,7 +2516,7 @@ public class CompileTimeErrorCodeTest extends ResolverTestCase {
         "  const A(String p) : a = true && p;",
         "}"));
     resolve(source);
-    assertErrors(CompileTimeErrorCode.NON_CONSTANT_VALUE_IN_INITIALIZER);
+    assertErrors(CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL);
     verify(source);
   }
 
@@ -2521,7 +2528,7 @@ public class CompileTimeErrorCodeTest extends ResolverTestCase {
         "}"));
     resolve(source);
     assertErrors(
-        CompileTimeErrorCode.NON_CONSTANT_VALUE_IN_INITIALIZER,
+        CompileTimeErrorCode.CONST_EVAL_TYPE_INT,
         CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE);
     verify(source);
   }
@@ -2534,7 +2541,7 @@ public class CompileTimeErrorCodeTest extends ResolverTestCase {
         "}"));
     resolve(source);
     assertErrors(
-        CompileTimeErrorCode.NON_CONSTANT_VALUE_IN_INITIALIZER,
+        CompileTimeErrorCode.CONST_EVAL_TYPE_NUM,
         CompileTimeErrorCode.ARGUMENT_TYPE_NOT_ASSIGNABLE);
     verify(source);
   }