Fixes #466 - Infinite loop bug with zero width boxes using break-word.

Big thanks to @syjer for finding out where to start debugging this bug.

openhtmltopdf-core/src/main/java/com/openhtmltopdf/layout/Breaker.java

@@ -280,7 +280,8 @@ static LineBreakResult doBreakCharacters(
             nextCharBreak = charIterator.next();
         }
 
-        if (graphicsLength == avail) {
+        if (graphicsLength == avail &&
+            graphicsLength > 0) {
             // Exact fit..
             boolean needNewLine = currentString.length() > left;
 
@@ -314,7 +315,8 @@ static LineBreakResult doBreakCharacters(
             graphicsLength += splitWidth;
         }
 
-        if (graphicsLength <= avail) {
+        if (graphicsLength <= avail &&
+            graphicsLength > 0) {
             // The entire word fit.
             context.setWidth(graphicsLength);
             context.setEnd(nextCharBreak + context.getStart());
@@ -361,6 +363,7 @@ static LineBreakResult doBreakCharacters(
             // Empty string.
             context.setEnd(context.getStart());
             context.setWidth(0);
+            context.setNeedsNewLine(false);
 
             return LineBreakResult.CHAR_BREAKING_FINISHED;
         }

openhtmltopdf-examples/src/main/resources/visualtest/html/issue-466-infinite-loop-table-cell-box.html

@@ -1,6 +1,31 @@
+<div>
+
+<!-- Width zero with content -->
+<div style="width: 0;">GHI</div>
+<div style="width: 0; word-wrap: break-word;">DEF</div>
+
+<!-- Width zero with breakable content -->
+<div style="width: 0;">PQR STU</div>
+<div style="width: 0; word-wrap: break-word;">VWX 123</div>
+
+<!-- Width zero with no content -->
+<div style="width: 0;"></div>
+<div style="width: 0; word-wrap: break-word;"></div>
+
+<!-- Negative content width with content -->
+<div style="box-sizing: border-box; width: 5px; padding: 0 5px;">JKL</div>
+<div style="box-sizing: border-box; width: 5px; padding: 0 5px; word-wrap: break-word;">MNO</div>
+
+<!-- Negative content width without content -->
+<div style="box-sizing: border-box; width: 5px; padding: 0 5px;"></div>
+<div style="box-sizing: border-box; width: 5px; padding: 0 5px; word-wrap: break-word;"></div>
+
+<!-- Zero width table cell as result of layout -->
 <table style="width: 3px;table-layout: fixed;">
 <tr>
  <td colspan="2"></td>
  <td style="word-wrap: break-word;">ABC</td>
 </tr>
 </table>
+
+</div>

openhtmltopdf-examples/src/test/java/com/openhtmltopdf/visualregressiontests/VisualRegressionTest.java

@@ -1019,9 +1019,12 @@ public void testIssue459RemUnitDefault() throws IOException {
     /**
      * Tests a reported infinite loop bug with table cells in specific
      * circumstances.
+     * 
+     * Turns out this bug was triggered by zero width table cells
+     * with content and word-wrap: break-word. Therefore, this test
+     * also exercises zero width divs with content (and without).
      */
     @Test
-    @Ignore // Infinite loop w memory allocation.
     public void testIssue466InfiniteLoopTableCellBox() throws IOException {
          assertTrue(vt.runTest("issue-466-infinite-loop-table-cell-box"));
     }