Set Firefox 79 as the minimum supported version

diff --git a/emsdk_manifest.json b/emsdk_manifest.json
index 6aecd85..b1a6f7a 100644
--- a/emsdk_manifest.json
+++ b/emsdk_manifest.json

@@ -343,29 +343,7 @@
 
   {
     "id": "firefox",
-    "version": "65.0",
-    "bitness": 64,
-    "url": "downloaded via mozdownload script, but a dummy directive is placed here so emsdk understands this Tool to be downloaded from the web",
-    "activated_cfg": "EMSDK_ACTIVATED_TEST_BROWSER=%installation_dir%/firefox%.exe%",
-    "activated_env": "EMTEST_BROWSER=%installation_dir%/firefox%.exe%",
-    "mac_activated_cfg": "EMSDK_ACTIVATED_TEST_BROWSER=%installation_dir%/Contents/MacOS/firefox%.exe%",
-    "mac_activated_env": "EMTEST_BROWSER=%installation_dir%/Contents/MacOS/firefox%.exe%",
-    "custom_install_script": "download_firefox"
-  },
-  {
-    "id": "firefox",
-    "version": "68.12.0esr",
-    "bitness": 64,
-    "url": "downloaded via mozdownload script, but a dummy directive is placed here so emsdk understands this Tool to be downloaded from the web",
-    "activated_cfg": "EMSDK_ACTIVATED_TEST_BROWSER=%installation_dir%/firefox%.exe%",
-    "activated_env": "EMTEST_BROWSER=%installation_dir%/firefox%.exe%",
-    "mac_activated_cfg": "EMSDK_ACTIVATED_TEST_BROWSER=%installation_dir%/Contents/MacOS/firefox%.exe%",
-    "mac_activated_env": "EMTEST_BROWSER=%installation_dir%/Contents/MacOS/firefox%.exe%",
-    "custom_install_script": "download_firefox"
-  },
-  {
-    "id": "firefox",
-    "version": "78.15.0esr",
+    "version": "79.0",
     "bitness": 64,
     "url": "downloaded via mozdownload script, but a dummy directive is placed here so emsdk understands this Tool to be downloaded from the web",
     "activated_cfg": "EMSDK_ACTIVATED_TEST_BROWSER=%installation_dir%/firefox%.exe%",