Fix the computation of unitsPerEm when the fontMatrix has some negative coefficients

It's a follow-up of #18253.

src/core/fonts.js

@@ -799,7 +799,7 @@ function createOS2Table(properties, charstrings, override) {
   const unitsPerEm =
     override.unitsPerEm ||
     (properties.fontMatrix
-      ? 1 / Math.max(...properties.fontMatrix.slice(0, 4))
+      ? 1 / Math.max(...properties.fontMatrix.slice(0, 4).map(Math.abs))
       : 1000);
 
   // if the font units differ to the PDF glyph space units
@@ -3199,7 +3199,7 @@ class Font {
     }
 
     const unitsPerEm = properties.fontMatrix
-      ? 1 / Math.max(...properties.fontMatrix.slice(0, 4))
+      ? 1 / Math.max(...properties.fontMatrix.slice(0, 4).map(Math.abs))
       : 1000;
 
     const builder = new OpenTypeFileBuilder("\x4F\x54\x54\x4F");

test/pdfs/.gitignore

@@ -650,3 +650,4 @@
 !issue17998.pdf
 !pdfjs_wikipedia.pdf
 !bug1539074.pdf
+!bug1539074.1.pdf

test/test_manifest.json

@@ -10098,6 +10098,13 @@
     "rounds": 1,
     "type": "eq"
   },
+  {
+    "id": "bug1539074_1",
+    "file": "pdfs/bug1539074.1.pdf",
+    "md5": "d15c49142fda433323d3d35f2762cd33",
+    "rounds": 1,
+    "type": "eq"
+  },
   {
     "id": "bug1903731",
     "file": "pdfs/bug1903731.pdf",