Bug 1362907 - Fix a couple crashtests.

<select> doesn't allow first-line, which was causing some non-fatal
asserts.

The annotated crashtest overflows a bSize but it gets handled safely by
nsLineLayout.

MANUAL PUSH: Trivial orange fix CLOSED TREE

layout/forms/crashtests/crashtests.list

@@ -68,7 +68,7 @@ load 1405830.html
 load 1418477.html
 load 1432853.html
 asserts(1-4) load 1460787-1.html
-load 1464165-1.html
+asserts(1-4) load 1464165-1.html # Big sizes.
 load 1471157.html
 load 1488219.html
 load 1600207.html

layout/generic/nsBlockFrame.cpp

@@ -7951,7 +7951,8 @@ void nsBlockFrame::SetInitialChildList(ChildListID aListID,
          (pseudo == PseudoStyleType::cellContent &&
           !GetParent()->Style()->IsPseudoOrAnonBox()) ||
          pseudo == PseudoStyleType::fieldsetContent ||
-         pseudo == PseudoStyleType::buttonContent ||
+         (pseudo == PseudoStyleType::buttonContent &&
+          !GetParent()->IsComboboxControlFrame()) ||
          pseudo == PseudoStyleType::columnContent ||
          (pseudo == PseudoStyleType::scrolledContent &&
           !GetParent()->IsListControlFrame()) ||