Revert "Set Firefox 79 as the minimum supported version"

This reverts commit cdb956d7dd4e7b7d6ca1fe79d342b6cf89280aac.

emsdk_manifest.json

diff --git a/emsdk_manifest.json b/emsdk_manifest.json
index b1a6f7a..6aecd85 100644
--- a/emsdk_manifest.json
+++ b/emsdk_manifest.json
@@ -343,7 +343,29 @@
 
   {
     "id": "firefox",
-    "version": "79.0",
+    "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",
     "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%",