XFA - Fix layout issues

- PR #13554 is buggy, so this patch aims to fix bugs.
  - check if a component fits into its parent in taking into account the parent layout.
  - introduce method isSplittable for template nodes to know if a component can be splitted in case of overflow.

test/pdfs/xfa_candidate_petitions.pdf.link

@@ -0,0 +1 @@
+https://web.archive.org/web/20210509141453/https://www.sos.state.oh.us/globalassets/elections/directives/2020/dir2020-15_independentcandidatepetitions2020signedextended.pdf

test/test_manifest.json

@@ -946,6 +946,14 @@
        "enableXfa": true,
        "type": "eq"
     },
+    {  "id": "xfa_candidate_petitions",
+       "file": "pdfs/xfa_candidate_petitions.pdf",
+       "md5": "0db96a00667f8f58f94cf81022e69341",
+       "link": true,
+       "rounds": 1,
+       "enableXfa": true,
+       "type": "eq"
+    },
     {  "id": "xfa_annual_expense_report",
        "file": "pdfs/xfa_annual_expense_report.pdf",
        "md5": "06866e7a6bbc0346789208ef5f6e885c",

test/unit/xfa_tohtml_spec.js

@@ -60,6 +60,9 @@ describe("XFAFactory", function () {
       </subform>
       <subform name="second">
         <breakBefore targetType="pageArea" startNew="1"/>
+        <subform>
+          <draw w="1pt" h="1pt"><value><text>foo</text></value></draw>
+        </subform>
       </subform>
     </subform>
   </template>
@@ -133,7 +136,7 @@ describe("XFAFactory", function () {
     <subform name="root" mergeMode="matchTemplate">
       <pageSet>
         <pageArea>
-          <contentArea x="123pt" w="456pt" h="789pt"/>
+          <contentArea x="0pt" w="456pt" h="789pt"/>
           <medium stock="default" short="456pt" long="789pt"/>
           <field y="1pt" w="11pt" h="22pt" x="2pt">
             <ui>
@@ -146,6 +149,7 @@ describe("XFAFactory", function () {
         </pageArea>
       </pageSet>
       <subform name="first">
+        <draw w="1pt" h="1pt"><value><text>foo</text></value></draw>
       </subform>
     </subform>
   </template>