Issue 5148. Error on abstract method in concrete class needs to be a warning

compiler/java/com/google/dart/compiler/resolver/Resolver.java

Index: compiler/java/com/google/dart/compiler/resolver/Resolver.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/Resolver.java b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
index f577e91bb62dc51d0a66e9a17bc9094bebb73ae0..7746fe2fd1f14d44f2bbb1c7e48721fe35af90ad 100644
--- a/compiler/java/com/google/dart/compiler/resolver/Resolver.java
+++ b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
@@ -656,13 +656,14 @@ public class Resolver {
         isAbstractClass = cl.getModifiers().isAbstract();
       }
 
-      if (body == null
-          && !Elements.isNonFactoryConstructor(member)
-          && !member.getModifiers().isAbstract()
-          && !member.getModifiers().isExternal()
-          && node.getRedirectedTypeName() == null
-          && !(isInterface || isAbstractClass)) {
-        onError(functionNode, ResolverErrorCode.METHOD_MUST_HAVE_BODY);
+      if (body == null) {
+        if (member.getModifiers().isStatic() && !member.getModifiers().isExternal()) {
+          onError(functionNode, ResolverErrorCode.STATIC_METHOD_MUST_HAVE_BODY);
+        } else if (!Elements.isNonFactoryConstructor(member) && !member.getModifiers().isAbstract()
+            && !member.getModifiers().isExternal() && node.getRedirectedTypeName() == null
+            && !(isInterface || isAbstractClass)) {
+          onError(functionNode, ResolverErrorCode.METHOD_MUST_HAVE_BODY);
+        }
       }
       resolve(functionNode.getBody());