Qualify the precompiled shared library name with the snapshot directory instead of using LD_LIBRARY…

tools/testing/dart/runtime_configuration.dart

Index: tools/testing/dart/runtime_configuration.dart
diff --git a/tools/testing/dart/runtime_configuration.dart b/tools/testing/dart/runtime_configuration.dart
index c2b2aed59ffe4b2a2856d179251c6f19a442f6fa..55cf8fe584c9966d9830685a2987a4f2a2283713 100644
--- a/tools/testing/dart/runtime_configuration.dart
+++ b/tools/testing/dart/runtime_configuration.dart
@@ -270,11 +270,10 @@ class DartPrecompiledRuntimeConfiguration extends DartVmRuntimeConfiguration {
     augmentedArgs.add("--run-precompiled-snapshot=${artifact.filename}");
     augmentedArgs.addAll(arguments);
 
-    var augmentedEnv = new Map.from(environmentOverrides);
-    augmentedEnv['LD_LIBRARY_PATH'] = artifact.filename;
-
     return <Command>[commandBuilder.getVmCommand(
-          suite.dartPrecompiledBinaryFileName, augmentedArgs, augmentedEnv)];
+        suite.dartPrecompiledBinaryFileName,
+        augmentedArgs,
+        environmentOverrides)];
   }
 }