Support column-based breakpoints in the VM and Observatory.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 331953f362352579854f4db08ac261410f3d9c4c..4cc1f50da146a789e4a03327efcce68d42c1b476 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -3182,7 +3182,9 @@ class Script : public Object {
   void SetLocationOffset(intptr_t line_offset, intptr_t col_offset) const;
 
   void GetTokenLocation(intptr_t token_pos,
-                        intptr_t* line, intptr_t* column) const;
+                        intptr_t* line,
+                        intptr_t* column,
+                        intptr_t* token_len = NULL) const;
 
   // Returns index of first and last token on the given line. Returns both
   // indices < 0 if no token exists on or after the line. If a token exists