gc'able AST for changed files

java/java-tests/testSrc/com/intellij/psi/AstLeaksTest.groovy

@@ -29,7 +29,7 @@ import com.intellij.codeInspection.defaultFileTemplateUsage.DefaultFileTemplateU
  */
 class AstLeaksTest extends LightCodeInsightFixtureTestCase {
 
-  public void "_test AST should be on a soft reference, for changed files as well"() {
+  public void "test AST should be on a soft reference, for changed files as well"() {
     def file = myFixture.addClass('class Foo {}').containingFile
     assert file.findElementAt(0) instanceof PsiKeyword
     LeakHunter.checkLeak(file, JavaFileElement)

platform/core-impl/src/com/intellij/psi/impl/source/PsiFileImpl.java

@@ -129,7 +129,7 @@ public abstract class PsiFileImpl extends ElementBase implements PsiFileEx, PsiF
   public FileElement getTreeElementNoLock() {
     ASTNode node = _getTreeElement();
     if (node == null && !getViewProvider().isPhysical()) {
-      setTreeElement(node = loadTreeElement());
+      node = loadTreeElement();
     }
     return (FileElement)node;
   }
@@ -400,7 +400,6 @@ public abstract class PsiFileImpl extends ElementBase implements PsiFileEx, PsiF
   private void doClearCaches() {
     final FileElement tree = getTreeElement();
     if (tree != null) {
-      myTreeElementPointer = tree;
       tree.clearCaches();
     }