Don't append '_' to the end of prefix in long name mapping if the original name starts with '_'

Otherwise we will have '__' which is illegal.
Review URL: https://codereview.appspot.com/5978058

git-svn-id: https://angleproject.googlecode.com/svn/trunk@1044 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/common/version.h b/src/common/version.h
index 1fa349a..a2ff426 100644
--- a/src/common/version.h
+++ b/src/common/version.h
@@ -1,7 +1,7 @@
 #define MAJOR_VERSION 1
 #define MINOR_VERSION 0
 #define BUILD_VERSION 0
-#define BUILD_REVISION 1041
+#define BUILD_REVISION 1044
 
 #define STRINGIFY(x) #x
 #define MACRO_STRINGIFY(x) STRINGIFY(x)
diff --git a/src/compiler/MapLongVariableNames.cpp b/src/compiler/MapLongVariableNames.cpp
index 0c7e1a9..a503101 100644
--- a/src/compiler/MapLongVariableNames.cpp
+++ b/src/compiler/MapLongVariableNames.cpp
@@ -15,7 +15,9 @@
     stream << "webgl_";
     if (isGlobal)
         stream << "g";
-    stream << id << "_";
+    stream << id;
+    if (name[0] != '_')
+        stream << "_";
     stream << name.substr(0, MAX_SHORTENED_IDENTIFIER_SIZE - stream.str().size());
     return stream.str();
 }