Minor: improve rendering of Traces in debugger

- add toString for ObservableBindingTrace (for debugging)
- add toString for LockProtectedTrace (for debugging)
- extract anonymous AbstractFilteringTrace to EffectFilteringTrace

compiler/frontend/src/org/jetbrains/kotlin/resolve/ObservableBindingTrace.java

@@ -97,4 +97,9 @@ public class ObservableBindingTrace implements BindingTrace {
     public boolean wantsDiagnostics() {
         return originalTrace.wantsDiagnostics();
     }
+
+    @Override
+    public String toString() {
+        return "ObservableTrace over " + originalTrace.toString();
+    }
 }

compiler/frontend/src/org/jetbrains/kotlin/storage/LockBasedLazyResolveStorageManager.kt

@@ -84,5 +84,9 @@ class LockBasedLazyResolveStorageManager(private val storageManager: StorageMana
         }
 
         override fun wantsDiagnostics() = trace.wantsDiagnostics()
+
+        override fun toString(): String {
+            return "Lock-protected trace of LockBasedLazyResolveStorageManager $storageManager"
+        }
     }
 }

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/ExpressionTypingServices.java

@@ -258,12 +258,7 @@ public class ExpressionTypingServices {
         boolean isFirstStatement = true;
         for (Iterator<? extends KtElement> iterator = block.iterator(); iterator.hasNext(); ) {
             // Use filtering trace to keep effect system cache only for one statement
-            AbstractFilteringTrace traceForSingleStatement = new AbstractFilteringTrace(context.trace, "trace for single statement") {
+            AbstractFilteringTrace traceForSingleStatement = new EffectsFilteringTrace(context.trace);
-                @Override
-                protected <K, V> boolean shouldBeHiddenFromParent(@NotNull WritableSlice<K, V> slice, K key) {
-                    return slice == BindingContext.EXPRESSION_EFFECTS;
-                }
-            };
 
             newContext = newContext.replaceBindingTrace(traceForSingleStatement);
 
@@ -375,4 +370,14 @@ public class ExpressionTypingServices {
         return result;
     }
 
+    private static class EffectsFilteringTrace extends AbstractFilteringTrace {
+        public EffectsFilteringTrace(BindingTrace parentTrace) {
+            super(parentTrace, "Effects filtering trace");
+        }
+
+        @Override
+        protected <K, V> boolean shouldBeHiddenFromParent(@NotNull WritableSlice<K, V> slice, K key) {
+            return slice == BindingContext.EXPRESSION_EFFECTS;
+        }
+    }
 }