Bug 571174 - [performance] improve getLineSeperator()

Old implementation did read files byte by byte.
This is a hot spot in junit test of JDT.

Bug: 571174
Change-Id: Ib08f643c38c51e01c5838743190ca54f591545b1
Signed-off-by: jkubitz <jkubitz-eclipse@gmx.de>

bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/utils/FileUtil.java

diff --git a/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/utils/FileUtil.java b/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/utils/FileUtil.java
index bf506e4..9b3d44b 100644
--- a/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/utils/FileUtil.java
+++ b/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/utils/FileUtil.java
@@ -287,7 +287,9 @@
 	public static String getLineSeparator(IFile file) {
 		if (file.exists()) {
 			try (
-				InputStream input = file.getContents()
+					// for performance reasons the buffer size should
+					// reflect the average length of the first Line:
+					InputStream input = new BufferedInputStream(file.getContents(), 128);
 			) {
 				int c = input.read();
 				while (c != -1 && c != '\r' && c != '\n')