Fix RenderTextTest.PangoAttributes test leaks; remove suppressions.

tools/heapcheck/suppressions.txt

Index: tools/heapcheck/suppressions.txt
diff --git a/tools/heapcheck/suppressions.txt b/tools/heapcheck/suppressions.txt
index f34ae64e7e76e3bcdf05e512f018ac0b7a12436a..34c45d66d2dff6b3de1b38c259baaf9253e23128 100644
--- a/tools/heapcheck/suppressions.txt
+++ b/tools/heapcheck/suppressions.txt
@@ -1804,22 +1804,3 @@
    ...
    fun:chromeos::MagnificationManagerTest_MagnificationObserver_Test::TestBody
 }
-{
-   bug_173597_a
-   Heapcheck:Leak
-   fun:g_realloc
-   fun:gfx::RenderTextTest_PangoAttributes_Test::TestBody
-}
-{
-   bug_173597_b
-   Heapcheck:Leak
-   fun:??
-   fun:gfx::RenderTextTest_PangoAttributes_Test::TestBody
-}
-{
-   bug_173597_c
-   Heapcheck:Leak
-   fun:FcConfigEvaluate
-   fun:gfx::RenderTextLinux::EnsureLayout
-   fun:gfx::RenderTextTest_PangoAttributes_Test::TestBody
-}