Step back and remove more getNode() invocations

compiler/java/com/google/dart/compiler/common/AbstractNode.java

Index: compiler/java/com/google/dart/compiler/common/AbstractNode.java
diff --git a/compiler/java/com/google/dart/compiler/common/AbstractNode.java b/compiler/java/com/google/dart/compiler/common/AbstractNode.java
index 16d1c8b6da5f4f05b4609b817c06d93cb9ea7c14..43ebdaf6a1df9b38324510600ba7c09b746c5b91 100644
--- a/compiler/java/com/google/dart/compiler/common/AbstractNode.java
+++ b/compiler/java/com/google/dart/compiler/common/AbstractNode.java
@@ -7,17 +7,17 @@ package com.google.dart.compiler.common;
 /**
  * Abstract base class for nodes that carry source information.
  */
-public class AbstractNode implements HasSourceInfo {
+public class AbstractNode implements HasSourceInfo, HasSourceInfoSetter {
 
   private SourceInfo sourceInfo = SourceInfo.UNKNOWN;
 
   @Override
-  public SourceInfo getSourceInfo() {
+  public final SourceInfo getSourceInfo() {
     return sourceInfo;
   }
 
   @Override
-  public void setSourceInfo(SourceInfo info) {
-    sourceInfo = info;
+  public final void setSourceInfo(SourceInfo sourceInfo) {
+    this.sourceInfo = sourceInfo;
   }
 }