Fix millisecond check in IsIsoTimeFormat()

Missing zero in constant 1000.

-- Tidy initialization while at it.

Change-Id: I94522738a486460105a5ceac7120f980cd37d4ba
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/109070
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/fxjs/xfa/cfxjse_formcalc_context.cpp b/fxjs/xfa/cfxjse_formcalc_context.cpp
index fab90c5..04cbecd 100644
--- a/fxjs/xfa/cfxjse_formcalc_context.cpp
+++ b/fxjs/xfa/cfxjse_formcalc_context.cpp
@@ -658,17 +658,15 @@
       return false;
 
     ++iIndex;
-    char szMilliSeconds[kSubSecondLength + 1];
+    char szMilliSeconds[kSubSecondLength + 1] = {};
     for (int j = 0; j < kSubSecondLength; ++j) {
       char c = pData[iIndex + j];
       if (!isdigit(c))
         return false;
       szMilliSeconds[j] = c;
     }
-    szMilliSeconds[kSubSecondLength] = '\0';
-
     iMilliSecond = FXSYS_atoi(szMilliSeconds);
-    if (iMilliSecond > 100) {
+    if (iMilliSecond >= 1000) {
       iMilliSecond = 0;
       return false;
     }