Fix an issue where the line extractor's trailing whitespace trimming sometimes trimmed a non-whitespace character

tsdoc/src/parser/LineExtractor.ts

@@ -151,7 +151,7 @@ export class LineExtractor {
             // Example: "/**\nL1*/"
 
             // (collectingLineStart was the start of this line)
-            collectingLineEnd = currentIndex;
+            collectingLineEnd = nextIndex;
             state = State.CollectingLine;
           }
           break;

tsdoc/src/parser/__tests__/__snapshots__/LineExtractor.test.ts.snap

@@ -266,10 +266,10 @@ Object {
   "comment": "/**[n][c][c][c][n]a[n] b[n] c [n]  d[n][c][c][c][n] */",
   "lines": Array [
     "[c][c][c]",
-    "",
-    " ",
-    " ",
-    "  ",
+    "a",
+    " b",
+    " c",
+    "  d",
     "[c][c][c]",
   ],
   "logMessages": Array [],