Fix parsing variable declaration in when subject

- parse destructuring declarations
- parse annotations on variable declaration in when subject

compiler/psi/src/org/jetbrains/kotlin/parsing/KotlinExpressionParsing.java

@@ -849,14 +849,16 @@ public class KotlinExpressionParsing extends AbstractKotlinParsing {
         if (at(LPAR)) {
             advanceAt(LPAR);
 
-            PsiBuilder.Marker property = mark();
+            PsiBuilder.Marker atWhenStart = mark();
             myKotlinParsing.parseModifierList(DEFAULT, TokenSet.create(EQ, RPAR));
             if (at(VAL_KEYWORD) || at(VAR_KEYWORD)) {
-                myKotlinParsing.parseLocalProperty(false);
-                property.done(PROPERTY);
+                IElementType declType = myKotlinParsing.parseProperty(KotlinParsing.PropertyParsingMode.LOCAL);
+
+                atWhenStart.done(declType);
+                atWhenStart.setCustomEdgeTokenBinders(PrecedingDocCommentsBinder.INSTANCE, TrailingCommentsBinder.INSTANCE);
             }
             else {
-                property.rollbackTo();
+                atWhenStart.drop();
                 parseExpression();
             }
 

compiler/psi/src/org/jetbrains/kotlin/psi/KtDestructuringDeclarationEntry.java

@@ -122,7 +122,8 @@ public class KtDestructuringDeclarationEntry extends KtNamedDeclarationNotStubbe
     @NotNull
     private ASTNode getParentNode() {
         ASTNode parent = getNode().getTreeParent();
-        assert parent.getElementType() == KtNodeTypes.DESTRUCTURING_DECLARATION;
+        assert parent.getElementType() == KtNodeTypes.DESTRUCTURING_DECLARATION :
+                "parent is " + parent.getElementType();
         return parent;
     }