Fix bug when a variable is used in try/catch and accessed trough HFieldGet and HFieldSet: reference…

lib/compiler/implementation/ssa/codegen.dart

Index: lib/compiler/implementation/ssa/codegen.dart
===================================================================
--- lib/compiler/implementation/ssa/codegen.dart	(revision 7979)
+++ lib/compiler/implementation/ssa/codegen.dart	(working copy)
@@ -1568,7 +1568,7 @@
   }
 
   visitFieldGet(HFieldGet node) {
-    if (node.receiver !== null) {
+    if (!node.isFromActivation()) {
       String name =
           compiler.namer.instanceFieldName(currentLibrary, node.name);
       beginExpression(JSPrecedence.MEMBER_PRECEDENCE);
@@ -1577,13 +1577,14 @@
       buffer.add(name);
       beginExpression(JSPrecedence.MEMBER_PRECEDENCE);
     } else {
-      buffer.add(JsNames.getValid(node.name.slowToString()));
+      String name = temporary(node.receiver);
+      buffer.add(name);
     }
   }
 
   visitFieldSet(HFieldSet node) {
     String name;
-    if (node.receiver !== null) {
+    if (!node.isFromActivation()) {
       name =
           compiler.namer.instanceFieldName(currentLibrary, node.name);
       beginExpression(JSPrecedence.ASSIGNMENT_PRECEDENCE);
@@ -1593,7 +1594,7 @@
     } else {
       // TODO(ngeoffray): Remove the 'var' once we don't globally box
       // variables used in a try/catch.
-      name = JsNames.getValid(node.name.slowToString());
+      String name = temporary(node.receiver);
       declareVariable(name);
     }
     buffer.add(' = ');