Change the handling of catch blocks to use context extension objects...

src/usage-analyzer.cc

Index: src/usage-analyzer.cc
===================================================================
--- src/usage-analyzer.cc	(revision 1089)
+++ src/usage-analyzer.cc	(working copy)
@@ -69,6 +69,7 @@
   void VisitRegExpLiteral(RegExpLiteral* node);
   void VisitObjectLiteral(ObjectLiteral* node);
   void VisitArrayLiteral(ArrayLiteral* node);
+  void VisitCatchExtensionObject(CatchExtensionObject* node);
   void VisitAssignment(Assignment* node);
   void VisitThrow(Throw* node);
   void VisitProperty(Property* node);
@@ -288,6 +289,11 @@
 }
 
 
+void UsageComputer::VisitCatchExtensionObject(CatchExtensionObject* node) {
+  Read(node->value());
+}
+
+
 void UsageComputer::VisitAssignment(Assignment* node) {
   if (node->op() != Token::ASSIGN)
     Read(node->target());