Per-closure breakpoints; restructure breakpoint implementation to keep a list of conditions.

runtime/vm/object_test.cc

Index: runtime/vm/object_test.cc
diff --git a/runtime/vm/object_test.cc b/runtime/vm/object_test.cc
index 5e72ebfe4343a587f4d3948fe38b15115a0bb715..4491df56472d6989ed4b34c123ec4d8fa6fa0406 100644
--- a/runtime/vm/object_test.cc
+++ b/runtime/vm/object_test.cc
@@ -4182,7 +4182,7 @@ TEST_CASE(FunctionWithBreakpointNotInlined) {
   EXPECT(func_b.CanBeInlined());
 
   // After setting a breakpoint in a function A.b, it is no longer inlineable.
-  SourceBreakpoint* bpt =
+  Breakpoint* bpt =
       Isolate::Current()->debugger()->SetBreakpointAtLine(name,
                                                           kBreakpointLine);
   ASSERT(bpt != NULL);