Disable line_height tests on Windows (flutter#6423)

Author: GaryQian

third_party/txt/src/txt/paragraph.h

@@ -206,7 +206,7 @@ class Paragraph {
   FRIEND_TEST(ParagraphTest, RepeatLayoutParagraph);
   FRIEND_TEST(ParagraphTest, Ellipsize);
   FRIEND_TEST(ParagraphTest, UnderlineShiftParagraph);
-  FRIEND_TEST(ParagraphTest, LineHeightsParagraph);
+  FRIEND_TEST_WINDOWS_DISABLED(ParagraphTest, LineHeightsParagraph);
 
   // Starting data to layout.
   std::vector<uint16_t> text_;

third_party/txt/src/txt/styled_runs.h

@@ -79,7 +79,7 @@ class StyledRuns {
   FRIEND_TEST(ParagraphTest, HyphenBreakParagraph);
   FRIEND_TEST(ParagraphTest, RepeatLayoutParagraph);
   FRIEND_TEST(ParagraphTest, Ellipsize);
-  FRIEND_TEST(ParagraphTest, LineHeightsParagraph);
+  FRIEND_TEST_WINDOWS_DISABLED(ParagraphTest, LineHeightsParagraph);
 
   struct IndexedRun {
     size_t style_index = 0;