Ignore not all, but only some problems in dart:core

compiler/java/com/google/dart/compiler/DartCompilerMainContext.java

Index: compiler/java/com/google/dart/compiler/DartCompilerMainContext.java
diff --git a/compiler/java/com/google/dart/compiler/DartCompilerMainContext.java b/compiler/java/com/google/dart/compiler/DartCompilerMainContext.java
index d45c00debc20c97e9989d79cf3096e087d45f973..642b35912ae016e35f52ecf08d209450ff9ba268 100644
--- a/compiler/java/com/google/dart/compiler/DartCompilerMainContext.java
+++ b/compiler/java/com/google/dart/compiler/DartCompilerMainContext.java
@@ -12,6 +12,8 @@ import com.google.dart.compiler.ast.LibraryUnit;
 import com.google.dart.compiler.metrics.CompilerMetrics;
 import com.google.dart.compiler.parser.DartParser;
 import com.google.dart.compiler.resolver.Elements;
+import com.google.dart.compiler.resolver.ResolverErrorCode;
+import com.google.dart.compiler.resolver.TypeErrorCode;
 
 import java.io.IOException;
 import java.io.Reader;
@@ -59,7 +61,17 @@ final class DartCompilerMainContext implements DartCompilerListener, DartCompile
     // problems in dart:core are not interesting
     // http://code.google.com/p/dart/issues/detail?id=7128
     if (Elements.isCoreLibrarySource(event.getSource())) {
-      return;
+      ErrorCode ec = event.getErrorCode();
+      if (ec == ResolverErrorCode.EXPECTED_CONSTANT_EXPRESSION_NUMBER
+          || ec == TypeErrorCode.ASSERT_BOOL
+          || ec == TypeErrorCode.TYPE_NOT_ASSIGNMENT_COMPATIBLE
+          || ec == TypeErrorCode.FOR_IN_WITH_INVALID_ITERATOR_RETURN_TYPE
+          || ec == TypeErrorCode.OPERATOR_EQUALS_BOOL_RETURN_TYPE
+          || ec == TypeErrorCode.CANNOT_OVERRIDE_TYPED_MEMBER
+          || ec == TypeErrorCode.CANNOT_OVERRIDE_METHOD_NOT_SUBTYPE
+          || ec == TypeErrorCode.OPERATOR_WRONG_OPERAND_TYPE) {
+        return;
+      }
     }
 
     // Remember error.