Let Lexer.getNumber treat a single decimal point as zero (issue 9252)

This is consistent with the behaviour in Adobe Reader.

test/pdfs/.gitignore

@@ -65,6 +65,7 @@
 !issue8823.pdf
 !issue9084.pdf
 !issue9105_reduced.pdf
+!issue9252.pdf
 !issue9262_reduced.pdf
 !issue9291.pdf
 !issue9458.pdf

test/pdfs/issue9252.pdf

@@ -0,0 +1,90 @@
+%PDF-1.4
+1 0 obj
+<<
+/Type /Catalog
+/Version /1.4
+/Pages 5 0 R
+/Outlines 3 0 R
+>>
+endobj
+2 0 obj
+<<
+/Title (Test)
+/Author (Test)
+/Creator (sharpPDF)
+/CreationDate (2017124)
+>>
+endobj
+3 0 obj
+<<
+/Type /Outlines
+/Count 0
+>>
+endobj
+4 0 obj
+<<
+/Type /Font
+/Subtype /Type1
+/Name /F1
+/BaseFont /Helvetica
+/Encoding /WinAnsiEncoding
+>>
+endobj
+5 0 obj
+<<
+/Type /Pages
+/Count 1
+/Kids [6 0 R ]
+>>
+endobj
+6 0 obj
+<<
+/Type /Page
+/Parent 5 0 R
+/Resources <</Font <</F1 4 0 R >>
+>>
+/MediaBox [0 0 612 792]
+/CropBox [0 0 612 792]
+/Rotate 0
+/ProcSet [/PDF /Text /ImageC]
+/Contents [7 0 R ]
+>>
+endobj
+7 0 obj
+<<
+/Filter [/ASCIIHexDecode]
+/Length 105
+>>
+stream
+710A42540A2F46312031352054660A2E202E3539202E38342072670A3530203735302054640A28546573742920546A0A45540A51>
+endstream
+endobj
+0 19
+0000000000 65535 f
+0000000010 00000 n
+0000000098 00000 n
+0000000202 00000 n
+0000000254 00000 n
+0000000370 00000 n
+0000000491 00000 n
+0000000615 00000 n
+0000000743 00000 n
+0000000857 00000 n
+0000000976 00000 n
+0000001099 00000 n
+0000001226 00000 n
+0000001345 00000 n
+0000001464 00000 n
+0000001585 00000 n
+0000001710 00000 n
+0000001777 00000 n
+0000002102 00000 n
+trailer
+<<
+/Size 102
+/Root 1 0 R
+/Info 2 0 R
+>>
+startxref
+36673
+%%EOF

test/test_manifest.json

@@ -741,6 +741,13 @@
        "lastPage": 1,
        "type": "eq"
     },
+    {  "id": "issue9252",
+       "file": "pdfs/issue9252.pdf",
+       "md5": "c7d039d808d9344a95d2c9cfa7586ca3",
+       "rounds": 1,
+       "link": false,
+       "type": "eq"
+    },
     {  "id": "issue9262",
        "file": "pdfs/issue9262_reduced.pdf",
        "md5": "5347ce2d7b3866625c22e115fd90e0de",

test/unit/parser_spec.js

@@ -14,6 +14,7 @@
  */
 
 import { Lexer, Linearization } from '../../src/core/parser';
+import { FormatError } from '../../src/shared/util';
 import { Name } from '../../src/core/primitives';
 import { StringStream } from '../../src/core/stream';
 
@@ -69,6 +70,23 @@ describe('parser', function() {
       expect(plusLexer.getNumber()).toEqual(205.88);
     });
 
+    it('should treat a single decimal point as zero', function() {
+      let input = new StringStream('.');
+      let lexer = new Lexer(input);
+
+      expect(lexer.getNumber()).toEqual(0);
+
+      let numbers = ['..', '-.', '+.', '-\r\n.', '+\r\n.'];
+      for (let number of numbers) {
+        let input = new StringStream(number);
+        let lexer = new Lexer(input);
+
+        expect(function() {
+          return lexer.getNumber();
+        }).toThrowError(FormatError, /^Invalid number:\s/);
+      }
+    });
+
     it('should handle glued numbers and operators', function() {
       var input = new StringStream('123ET');
       var lexer = new Lexer(input);