Trim a line on the right before determining max breakpoint column

runtime/observatory/lib/src/debugger/debugger_location.dart

Index: runtime/observatory/lib/src/debugger/debugger_location.dart
diff --git a/runtime/observatory/lib/src/debugger/debugger_location.dart b/runtime/observatory/lib/src/debugger/debugger_location.dart
index b6114d24320d36df96c3996bc8963c2917b854f0..31facf20f0ba3dd1d0456e15aa74447f828c0b38 100644
--- a/runtime/observatory/lib/src/debugger/debugger_location.dart
+++ b/runtime/observatory/lib/src/debugger/debugger_location.dart
@@ -420,7 +420,7 @@ class DebuggerLocation {
         }
         var sharedPrefix = '${script.name}:${lineStr}:';
         List completions = [];
-        int maxCol = scriptLine.text.runes.length;
+        int maxCol = scriptLine.text.trimRight().runes.length;
         for (int i = 1; i <= maxCol; i++) {
           var currentColStr = i.toString();
           if (currentColStr.startsWith(colStr)) {