Debugger: use debug break slots instead of ICs (except for calls).

test/mjsunit/debug-backtrace.js

Index: test/mjsunit/debug-backtrace.js
diff --git a/test/mjsunit/debug-backtrace.js b/test/mjsunit/debug-backtrace.js
index b4fb2c8535a6dbde73d95bdd61af7ad71c964fb1..01775f560eae0abe40ac7cbcaf0447c664ac54bb 100644
--- a/test/mjsunit/debug-backtrace.js
+++ b/test/mjsunit/debug-backtrace.js
@@ -165,7 +165,7 @@ function listener(event, exec_state, event_data, data) {
       assertEquals("f", response.lookup(frame.func.ref).name);
       assertTrue(frame.constructCall);
       assertEquals(31, frame.line);
-      assertEquals(3, frame.column);
+      assertEquals(2, frame.column);
       assertEquals(2, frame.arguments.length);
       assertEquals('x', frame.arguments[0].name);
       assertEquals('number', response.lookup(frame.arguments[0].value.ref).type);
@@ -179,7 +179,7 @@ function listener(event, exec_state, event_data, data) {
       assertEquals(0, frame.index);
       assertEquals("f", response.lookup(frame.func.ref).name);
       assertEquals(31, frame.line);
-      assertEquals(3, frame.column);
+      assertEquals(2, frame.column);
       assertEquals(2, frame.arguments.length);
       assertEquals('x', frame.arguments[0].name);
       assertEquals('number', response.lookup(frame.arguments[0].value.ref).type);