Update test to match commit 0daba829.

i.e. change I93ccdd10af96525c8df0dcd323a6000394925c39

Downcasting isn't safe.  Asserting on a string isn't ideal either, but
Position doesn't have a method exposing line numbers.

Change-Id: I2e02dd275b605f7a9f5561fe29762cc582b7579f
diff --git a/src/test/java/com/android/tools/r8/naming/SeedMapperTests.java b/src/test/java/com/android/tools/r8/naming/SeedMapperTests.java
index d420618..e7511bd 100644
--- a/src/test/java/com/android/tools/r8/naming/SeedMapperTests.java
+++ b/src/test/java/com/android/tools/r8/naming/SeedMapperTests.java
@@ -10,7 +10,6 @@
 import com.android.tools.r8.Diagnostic;
 import com.android.tools.r8.TestBase;
 import com.android.tools.r8.TestDiagnosticMessagesImpl;
-import com.android.tools.r8.position.TextPosition;
 import com.android.tools.r8.utils.AbortException;
 import com.android.tools.r8.utils.FileUtils;
 import com.android.tools.r8.utils.Reporter;
@@ -58,7 +57,7 @@
       assertEquals(
           String.format(ProguardMapError.DUPLICATE_SOURCE_MESSAGE, "A.B.C"),
           diagnostic.getDiagnosticMessage());
-      assertEquals(2, ((TextPosition) diagnostic.getPosition()).getLine());
+      assertEquals("line 2", diagnostic.getPosition().getDescription());
     }
   }
 
@@ -81,7 +80,7 @@
       assertEquals(
           String.format(ProguardMapError.DUPLICATE_SOURCE_MESSAGE, "int aaaa(B)"),
           diagnostic.getDiagnosticMessage());
-      assertEquals(3, ((TextPosition) diagnostic.getPosition()).getLine());
+      assertEquals("line 3", diagnostic.getPosition().getDescription());
     }
   }
 
@@ -104,7 +103,7 @@
       assertEquals(
           String.format(ProguardMapError.DUPLICATE_SOURCE_MESSAGE, "int aaaa"),
           diagnostic.getDiagnosticMessage());
-      assertEquals(3, ((TextPosition) diagnostic.getPosition()).getLine());
+      assertEquals("line 3", diagnostic.getPosition().getDescription());
     }
   }
 
@@ -122,7 +121,7 @@
       assertEquals(
           String.format(ProguardMapError.DUPLICATE_TARGET_MESSAGE, "A.B.D", "A.B.C", "a"),
           diagnostic.getDiagnosticMessage());
-      assertEquals(2, ((TextPosition) diagnostic.getPosition()).getLine());
+      assertEquals("line 2", diagnostic.getPosition().getDescription());
     }
   }
 
@@ -161,7 +160,7 @@
       assertEquals(
           String.format(ProguardMapError.DUPLICATE_TARGET_MESSAGE, "int bar(A)", "int foo(A)", "a"),
           diagnostic.getDiagnosticMessage());
-      assertEquals(2, ((TextPosition) diagnostic.getPosition()).getLine());
+      assertEquals("line 2", diagnostic.getPosition().getDescription());
     }
   }