Make ASAN happy in MHTMLTest.TestMHTMLEncoding

Source/web/tests/MHTMLTest.cpp

Index: Source/web/tests/MHTMLTest.cpp
diff --git a/Source/web/tests/MHTMLTest.cpp b/Source/web/tests/MHTMLTest.cpp
index 4fbd4380e7f807ccfcb77d5fcbc0374878e6bf4c..b15370df36331c7147b381ac63667d2443da5e1d 100644
--- a/Source/web/tests/MHTMLTest.cpp
+++ b/Source/web/tests/MHTMLTest.cpp
@@ -185,7 +185,7 @@ TEST_F(MHTMLTest, TestMHTMLEncoding)
     RefPtr<SharedBuffer> data  = serialize("Test Serialization", "text/html", MHTMLArchive::UseDefaultEncoding);
 
     // Read the MHTML data line per line and do some pseudo-parsing to make sure the right encoding is used for the different sections.
-    LineReader lineReader(std::string(data->data()));
+    LineReader lineReader(std::string(data->data(), data->size()));
     int sectionCheckedCount = 0;
     const char* expectedEncoding = 0;
     std::string line;